Rear Spring size/interchange
 

Is there a difference between Springs on a C-10 and a C-20?
Beside the Spring rate.. Is a c20 spring able to "Bolt On" a C10 and maintain the same ride height of the c10?
If the coil is a larger size rod on a c20 will the mount plates bolt on a C10 trailing arm?

Re: Rear Spring size/interchange
 

I'll attempt two questions :
When I bought my 65 back, someone put a piece of diamond plate steel for the bed. They also put air shocks on it. The 1/2 ton springs weren't strong enough to keep the bed from dropping so low that the fenders rubbed on the wide tires.
I was able to swap out the 1/2 ton springs with 3/4 ton springs with no mods. 1/2 ton coil base brackets worked fine with the 3/4 ton coil springs. For me, going from C10 to C20 springs raised my truck up in the back quite a bit.

Re: Rear Spring size/interchange
 

Thanks for the information.. Its hard to tell about ride height,, I think the only way to know is add a set of 3/4 on and see if I drive downhill all over..

Re: Rear Spring size/interchange
 

should be able to find weight and hight specs online.

Re: Rear Spring size/interchange
 

Some springs seem to be much stronger than others. I had a 68 C10 short box that I got 1.8 ton of gravel on and it took all of that to plant it on the stops. When the scale guy told me what was on it I wasn't going to shovel it off until I got home or a wheel fell off. I could just envision that happening going over the Granville street bridge from the airport in Vancouver. Luckily it made it.

The new springs I put under the 66 are much softer and go down an inch or two by just stepping on the bumper.