Looking for the right Chevy truck parts for your build? G Force Performance Products offers transmission crossmembers, LS engine swap motor mounts, Cummins conversion kits, and transmission adapter plates for classic Chevrolet C10 pickups, square-body Chevy trucks, and 1988–1998 OBS Chevy and GMC trucks.
Whether you're upgrading a 1967–1972 C10, building a 1973–1987 square-body pickup, or putting an LS or Cummins diesel into a 1988–1998 OBS Chevy, getting the engine and transmission mounted correctly is a big part of building a dependable truck.
This guide breaks down the major Chevy truck parts categories by model year, explains which crossmembers and swap kits to consider, and answers common questions about transmission compatibility, exhaust clearance, and Cummins conversions.
Shop the parts directly from G Force Performance Products at Crossmembers.com.
Before ordering a crossmember or engine swap kit, identify your truck's model year, whether it's two-wheel drive or four-wheel drive, and which engine and transmission combination you're planning to run.
Two trucks that look similar from the outside can require different mounting components underneath.
Chevy truck fitment comparison chart
|
Truck generation |
Model years |
Common project |
G Force parts to consider |
|---|---|---|---|
|
Classic C10 |
1967–1972 |
Transmission upgrade or LS swap |
RCC-10-2, RCC-10-2-PRO |
|
Square-body C10 |
1973–1987 |
Transmission upgrade, LS swap |
RCC-10-3, RCC10-3-PRO |
|
Square-body C/K 4WD |
1973–1987 |
5.9L Cummins diesel swap |
GF-GMK3-KIT |
|
OBS Chevy/GMC |
1988–1998 |
Transmission upgrade or LS swap |
RCC10-4-PRO, GF-OBSLSMM-KIT |
|
OBS Chevy/GMC 4WD |
1988–1998 |
5.9L Cummins diesel swap |
GF-C4-MM-KIT |
Important: Crossmember and engine-mount fitment are not interchangeable across every generation. Several crossmembers listed below are specifically for two-wheel-drive trucks, while the Cummins motor mount kits have their own drivetrain requirements. Always verify the complete product specifications before ordering.
A transmission crossmember does more than hold the transmission in place. It helps support the drivetrain, maintain the intended transmission mounting position, and provide clearance for exhaust components.
When you're replacing an old crossmember or installing a different transmission, the right design can save time during installation and reduce the need to fabricate mounting solutions.
G Force offers C10 transmission crossmembers for two popular generations of Chevrolet pickups.
1967–1972 Chevy C10 transmission crossmembers
The 1967–1972 Chevrolet C10 is a popular platform for classic truck restorations, pro-touring builds, and modern drivetrain conversions.
G Force offers two options for this generation.
Standard C10 crossmember: RCC-10-2
The 1967–1972 Chevy C10 transmission crossmember, part RCC-10-2, is designed for two-wheel-drive GM C-Series pickups.
Key features include:
This is a useful option when you're refreshing an older truck's drivetrain or upgrading to a different transmission while keeping the original chassis.
Heavy-duty crossmember: RCC-10-2-PRO
The 1967–1972 C-Series truck RCC-10-2-PRO crossmember offers another option for builders looking for a crossmember with broad transmission compatibility.
It fits 1967–1972 C10 2WD trucks and supports numerous transmission applications, including the TH350, TH400 Short Tail, 700R4, 4L60, 4L80E, 2004R, T56-family transmissions, and several newer automatic transmissions.
Its design accommodates larger transmissions such as the 4L80E, although additional mounting holes or other modifications may be required depending on the application.
Which 1967–1972 crossmember should you choose?
Start with the transmission you're installing and the mounting arrangement you need. Compare the standard RCC-10-2 with the RCC-10-2-PRO on their individual product pages, paying particular attention to transmission compatibility, mounting requirements, and exhaust routing.
The 1973–1987 square-body Chevrolet C10 is another strong candidate for a drivetrain upgrade. These trucks are frequently built with modern LS engines, overdrive automatics, and performance-oriented manual transmissions.
G Force offers two crossmember options for this generation.
Standard LS-swap crossmember: RCC-10-3
The 1973–1987 Chevy C10 LS-swap transmission crossmember, part RCC-10-3, is designed for C10 2WD trucks and combines stock-replacement functionality with LS-swap flexibility.
Highlights include:
The crossmember is designed to bolt into factory frame holes for most applications. Larger transmissions, including the 4L80E, may require repositioning or additional mounting holes.
For a truck that's getting an LS engine and an overdrive transmission, this crossmember is worth considering early in the build. Transmission position and exhaust routing are much easier to plan before the exhaust system is fabricated.
PRO crossmember: RCC10-3-PRO
The 1973–1987 C10 RCC10-3-PRO crossmember is another option for 2WD square-body trucks.
It supports a broad range of automatic and manual transmissions, including the TH350, 700R4, 4L60E, 2004R, 4L80E, T56 Magnum, TR6060, and selected newer GM automatic transmissions.
Its design accommodates larger heavy-duty transmissions, although some applications may require adjustments or additional mounting holes.
The product includes mounting hardware and a G Force adjustable transmission mount for proper positioning.
Choosing between the RCC-10-3 and RCC10-3-PRO
|
Feature |
RCC-10-3 |
RCC10-3-PRO |
|---|---|---|
|
Truck fitment |
1973–1987 C10 2WD |
1973–1987 C10 2WD |
|
LS-swap applications |
Yes |
Yes |
|
Dual-exhaust clearance |
Yes |
Yes |
|
Transmission compatibility |
Broad range |
Broad range |
|
Mounting hardware |
Included |
Included |
|
Transmission mount |
Verify product configuration |
Adjustable mount included |
Both are intended for 2WD applications, not four-wheel-drive trucks. Check the current product listings for the exact transmission and mounting requirements for your build.
The 1988–1998 Chevy and GMC trucks are commonly called OBS trucks, short for old body style. The GMT400 platform remains popular for daily drivers, street trucks, work trucks, and LS conversions.
If you're upgrading a C1500 or another compatible two-wheel-drive GMT400 truck, the G Force RCC10-4-PRO is designed to accommodate a range of transmission combinations.
The 1988–1998 Chevy/GMC C1500 transmission crossmember, part RCC10-4-PRO, is designed for 2WD C1500, C2500, C3500, GMT400, and Suburban applications listed by G Force.
Key features:
Most applications use the factory crossmember mounting holes. Some early-model trucks installing a 4L80E may require new frame mounting holes.
The dual-hump design is intended to help route exhaust underneath the crossmember while keeping it above the frame rails. However, actual clearance depends on the exhaust configuration, transmission, and other installed components.
An LS swap isn't just an engine installation. The transmission mount, driveshaft alignment, exhaust routing, and overall drivetrain position also need to work together.
A compatible crossmember gives you a defined mounting solution instead of leaving you to solve those issues with custom fabrication.
For a 1988–1998 OBS Chevy or GMC truck getting an LS engine and a different transmission, start by checking the RCC10-4-PRO specifications against your exact combination.
Shop the RCC10-4-PRO OBS Chevy/GMC transmission crossmember.
The LS engine family has become a popular choice for OBS truck builds because it offers a modern V8 platform with extensive aftermarket support.
But before installing an LS engine in an older truck, you need to address the engine mounting system. The correct motor mounts help establish engine position and provide the intended connection between the engine and chassis.
G Force offers an LS swap motor mount kit for compatible 1988–1998 Chevy and GMC applications.
The 1988–1998 Chevy/GMC LS swap motor mount kit, part GF-OBSLSMM-KIT, is designed for a range of OBS Chevrolet and GMC vehicles.
The listed applications include C1500, C2500, C3500, R30, V30, V3500, C1500 Suburban, Tahoe, and selected Express vans.
Features include:
The kit is designed for OBS truck LS conversions and also lists compatibility with several other engine categories. Review the product page to confirm your exact application.
NOTE: This motor mount kit will not work with a stepped style K-member. Only works with 3-bolt flat style.
Motor mounts are one part of the installation. A successful swap also requires attention to:
Not every LS engine, oil pan, exhaust manifold, or transmission combination fits the same way. Confirm clearances with your actual components before finalizing the installation.
Shop the GF-OBSLSMM-KIT LS swap motor mounts.
Want diesel torque in a classic Chevy pickup? A Cummins 5.9L 6BT conversion is a popular way to build a diesel-powered square-body truck or OBS Chevy.
A Cummins swap involves more than bolting an engine into the chassis. You must consider engine mounting, oil-pan clearance, transmission compatibility, starter fitment, and drivetrain alignment.
G Force offers both complete conversion kits and individual adapter components for these projects.
The 1973–1987 GM C-Series Cummins conversion kit, GF-GMC3-KIT, is designed for 2WD C-Series trucks using a 1989–2002 Cummins 6BT engine.
The kit includes key components for mating the Cummins engine to a compatible GM automatic transmission, including:
Compatible transmissions include the Chevrolet TH400, 700R4, and 4L80E.
A kit approach helps bring several essential conversion parts together rather than requiring you to source every component separately.
Four-wheel-drive square-body trucks have additional packaging challenges, particularly around the front differential and oil pan.
The 1973–1987 GM K-Series Cummins conversion kit, GF-GMK3-KIT, is designed for 4WD K-Series trucks and uses a 1989–2002 Cummins 6BT engine.
The kit includes a transmission adapter and flexplate, Cummins motor mounts, related bolt kits, and a two-inch-drop engine crossmember.
The drop crossmember is designed to help establish appropriate engine placement and can often eliminate the need for a body lift when used as specified.
Compatible transmissions include the TH400, 700R4, and 4L80E.
The distinction matters: The C-Series kit is for the listed 2WD applications; the K-Series kit is for the listed 4WD applications. Don't choose between them based on appearance alone.
The GF-C4-MM-KIT Cummins swap motor mount kit is designed for compatible 1988–1998 K1500, K2500, and K3500 four-wheel-drive trucks.
Key details:
G Force recommends upgraded front suspension for 1500 trucks to accommodate the additional engine weight.
Because this kit is specifically designed for 4WD applications, verify your chassis, engine, and suspension configuration before ordering.
One of the most important parts of a Cummins conversion is matching the engine to the transmission.
A transmission adapter plate and the appropriate flexplate create the mechanical connection between the engine and transmission. The correct kit depends on the Cummins engine year and the transmission you intend to use.
G Force offers Cummins-to-Chevy adapter kits for earlier 5.9L engines and later common-rail engines.
|
G Force part number |
Cummins engine years |
Transmission application |
Primary use |
|---|---|---|---|
|
GF-C-S |
1989–2002 |
TH400, 700R4, 4L80E |
Earlier 5.9L Cummins |
|
GF-C-SL |
2003–2025, as listed |
TH400, 700R4, 4L80E |
Later common-rail Cummins |
|
GF-A-S |
1989–2002 |
GM Allison application |
Earlier Cummins-to-Allison conversion |
|
GF-A-SL |
2003–2025, as listed |
GM Allison application |
Later Cummins-to-Allison conversion |
Always verify the exact transmission generation, bellhousing pattern, engine configuration, and current product specifications. The model-year range alone does not guarantee compatibility with every transmission.
The 1989–2002 Cummins-to-Chevy adapter kit, GF-C-S, is designed to mate an earlier 5.9L Cummins 6BT engine with a compatible Chevrolet automatic transmission.
Listed applications include:
The adapter and flexplate kit is intended to position the transmission straight rather than at an angle used by some original-equipment applications.
Starter note: This kit requires a Ford 6.4L Power Stroke starter, part GF-MS-FORD64. A Ford 6.0L starter may be an alternative, but some bellhousings require additional interior clearance. Certain applications may also require clearance modifications at the engine block pan rail and starter.
The adapter bolt kit is sold separately, so account for that when planning your parts order.
The 2003–2025 Cummins-to-Chevy adapter kit, GF-C-SL, is designed for later Cummins common-rail engines and compatible Chevrolet automatic transmissions.
Listed transmission applications include the TH400, 700R4, and 4L80E.
Like the earlier kit, the GF-C-SL uses an adapter plate and flexplate to mate the Cummins engine to the selected GM transmission.
The kit requires the specified Ford 6.4L Power Stroke starter, with the Ford 6.0L option subject to clearance considerations. Some combinations may require engine block pan-rail or starter clearance modifications.
Check the current listing carefully before ordering, particularly when working with a later 6.7L Cummins engine.
For builders planning to use a GM Allison automatic transmission behind a Cummins engine, G Force offers adapter kits for different Cummins engine generations.
The key is matching the engine's year range to the adapter and confirming the specific Allison transmission and bellhousing pattern.
The 1989–2002 Cummins-to-Allison adapter kit, GF-A-S, is designed for earlier 5.9L Cummins 6BT engines.
It accommodates the listed Cummins engines when paired with a compatible GM Allison transmission application or the specified Duramax bellhousing pattern.
The kit includes an adapter plate and flexplate. It also requires the specified Ford 6.4L Power Stroke starter, with the Ford 6.0L option subject to clearance considerations.
The 2003–2025 Cummins-to-Allison adapter kit, GF-A-SL, is intended for later Cummins common-rail engine conversions.
Confirm the exact Allison transmission, model year, and bellhousing configuration before purchasing. Compatibility depends on the particular transmission and engine combination, not just the Cummins engine's year.
These adapter kits are useful for builders putting together a custom diesel drivetrain, but they are not a substitute for checking the complete transmission and vehicle specifications.
When shopping for Chevy truck parts, narrow the options down in a logical order. That is usually faster than buying parts based on a general description and discovering a fitment issue halfway through the build.
Start with the model year and chassis:
This is particularly important for crossmembers and Cummins swap mounts. The C10 crossmembers discussed above are for 2WD applications, while the GF-GMK3-KIT and GF-C4-MM-KIT are designed for specified 4WD applications.
Write down the engine family, engine year, transmission model, and any aftermarket bellhousing or adapter already installed.
For Cummins conversions, distinguish between the 1989–2002 engines and later common-rail engines.
Consider transmission mount height, driveshaft length, exhaust clearance, oil-pan clearance, and any required frame modifications.
A crossmember that fits the chassis may still require adjustments for a particular transmission or exhaust setup.
Use the individual G Force product listing to verify fitment, included hardware, installation notes, and any required components that are sold separately.
If your combination falls outside the listed specifications, contact G Force before ordering
G Force offers the RCC-10-2 and RCC-10-2-PRO for listed 1967–1972 C10 2WD applications. Choose based on your transmission, mounting requirements, and exhaust configuration.
G Force offers the RCC-10-3 and RCC10-3-PRO for 1973–1987 C10 2WD trucks. Both support a range of automatic and manual transmissions and are designed to provide dual-exhaust clearance.
The G Force RCC10-4-PRO is designed for compatible 1988–1998 2WD Chevy and GMC trucks, including C1500 applications. It supports numerous transmission combinations and includes an adjustable transmission mount.
Yes. The GF-OBSLSMM-KIT is designed for listed 1988–1998 Chevy and GMC applications and includes polyurethane frame mounts and isolators.
View the OBS LS swap motor mount kit.
Yes, a Cummins conversion is possible with the appropriate engine mounts, transmission adapter, flexplate, and supporting components. G Force offers a C-Series kit for listed 1973–1987 2WD trucks and a K-Series kit for listed 1973–1987 4WD trucks.
The main starting point is the Cummins engine year and the transmission you want to use. G Force offers the GF-C-S for 1989–2002 Cummins engines and the GF-C-SL for listed 2003–2025 engines.
Verify starter requirements, bellhousing compatibility, and possible clearance modifications before ordering.
Not necessarily. The C10 crossmembers covered in this guide are specified for 2WD applications. Four-wheel-drive trucks may require different components to accommodate the front drivetrain and chassis layout.
Always follow the product's stated fitment.
The crossmembers featured in this guide list mounting hardware as included. Transmission mounts vary by product: for example, the RCC10-4-PRO includes an adjustable transmission mount, while other configurations may have different requirements.
Check the specific product page before ordering.
Whether you're restoring a classic C10, updating a square-body truck, building an OBS LS swap, or converting a Chevy to Cummins diesel power, start with the chassis and drivetrain combination you actually have.
G Force Performance Products offers transmission crossmembers, engine swap motor mounts, Cummins conversion kits, and transmission adapter plates to help you plan the installation around your truck's requirements.
Shop the G Force lineup:
Get the fitment right before the truck goes on the lift. It makes the rest of the build easier to plan and gives you a better starting point for a reliable drivetrain installation.
Always verify current fitment, included components, and installation requirements on the individual product page before purchasing.