The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - C10 vs 20 Suspension interchangeability or swapability ???

SkidmoreGarage · 06-14-2021, 11:59 PM

I just went through this on my build, feel free to browse my build thread. It is harder and more expensive than you would think and most of the guys who have multiple donor trucks/experience will make it seem easy in theory. But I think it's worth it!

The reasons for the challenge and expense are that most of the info online and "bolt on" kits are referencing c10 short bed stuff. If you buy a kit or research a part number it may require more modification than you had planned or re-engineering a bracket or tab. It's not that the two models are drastically different, it's that they are just similar enough that it would seem easy, but it isn't. The good news is that the front control arms and rear trailing arms bolt up in the same place, so you can't get too far off track. I would also keep in mind that some of the 5 bolt stuff has been getting harder to find used as the cost of these trucks have gone up, and may require additional cost to rehab as the used parts are 50 years old.

The differences:
The c20 frame is different, the rear axle is different (in my case conversion axles were not available), the panhard location on the frame may be different, the trailing arms are different (still usable but thicker at the u bolts), the axle u joints will likely change, the cab mounts are different, the front ball joints and spindles are different, and the springs are different. That's all I can remember off the top of my head but also there is the cost of the new wheels and tires to consider.

Now for the good news:
The c20 frame is made of 20% thicker material and has more factory bracing
A lot of the stuff that is replaced in the swap may already need replacing on an old truck
If you plan to upgrade/customize the rear end and add disc brakes it doesn't really matter that you have to replace what is usually under the c20/30 which is a 4.11 to 4.56 open diff.
When you are done the truck will be worth a lot more to more people
You may have planned to throw most of the old stuff out anyway, so it doesn't really matter.

06-14-2021, 11:59 PM	#2
SkidmoreGarage Registered User Join Date: Mar 2020 Location: Portland, OR Posts: 335	Re: C10 vs 20 Suspension interchangeability or swapability ??? I just went through this on my build, feel free to browse my build thread. It is harder and more expensive than you would think and most of the guys who have multiple donor trucks/experience will make it seem easy in theory. But I think it's worth it! The reasons for the challenge and expense are that most of the info online and "bolt on" kits are referencing c10 short bed stuff. If you buy a kit or research a part number it may require more modification than you had planned or re-engineering a bracket or tab. It's not that the two models are drastically different, it's that they are just similar enough that it would seem easy, but it isn't. The good news is that the front control arms and rear trailing arms bolt up in the same place, so you can't get too far off track. I would also keep in mind that some of the 5 bolt stuff has been getting harder to find used as the cost of these trucks have gone up, and may require additional cost to rehab as the used parts are 50 years old. The differences: The c20 frame is different, the rear axle is different (in my case conversion axles were not available), the panhard location on the frame may be different, the trailing arms are different (still usable but thicker at the u bolts), the axle u joints will likely change, the cab mounts are different, the front ball joints and spindles are different, and the springs are different. That's all I can remember off the top of my head but also there is the cost of the new wheels and tires to consider. Now for the good news: The c20 frame is made of 20% thicker material and has more factory bracing A lot of the stuff that is replaced in the swap may already need replacing on an old truck If you plan to upgrade/customize the rear end and add disc brakes it doesn't really matter that you have to replace what is usually under the c20/30 which is a 4.11 to 4.56 open diff. When you are done the truck will be worth a lot more to more people You may have planned to throw most of the old stuff out anyway, so it doesn't really matter.