C10/C20 K10/K20 Frame Interchangeability

[Wisconsin 72]

Hey all,
I'm new to the forum, but I'm trying to find out if a 67-72 C10/c20 frame has the same dimensions as a k10/k20 frame of the same model years. Basically I'm looking for a new frame for my 72 k20, but I cannot find a replacement 4x4 (k10/k20) for sale in the area (Mid WI). However I've found many 4x2 (c10/c20) frames for sale. Is it possible to convert a 4x2 frame to a 4x4 frame or are the frame rails different dimensions? Thanks!

[BurnoutNova]

The c10 or c20 frames do not have the front spring hangers, so you would need to swap those and the shackle hangers for the front leafsprings will need to be swapped also. There is a spot you need to weld up where the e brake cable goes through the frame, it is right in the way of where the front spring shackle goes. You will need to swap your engine crossmember, and the trans crossmember from your k20 frame also.

On the rear, most you'll find will be coil spring suspension, so you will need to swap over for the rear leaf springs. the rear rails are not parallel on a coil spring 2wd rear either, but you can make it work.

All in all its a lot of work, but it can be done.

[woodwright]

Look at my work truck build thread. I converted a 69 c10 frame over to a K10.

[Mike C]

If you want to just "swap" there are lots of differences. 2x4 has different spring hangers for the leafs (if it is a leaf truck, 2 1/4" wide on most 2x4, but Longhorn has 2 1/2" and they are shorter than 4x4 height wise). 42.5" spring centers if it is a 2x4 and 40" if it is a 4x4. You can make a 2x4 a 4x4, but it is not just a "swap parts" quickie.

[woodwright]

Definitely not a bolt on swap, but whats the fun in that