[66-PMD-GMC]

Originally Posted by SCOTI

My 'Recycle' build is based on a 68lwb frame but I don't have specific pics per say of the 'differences':

Front frame horns different height & physical shape
Radiator core support mounts (fore/aft location vs front x-member C/L)
Radiator core support mount height (63-66 core support vs. 67-72)
Front splash apron (specific to post 66 trucks?)
Rear cab mount height

I have seen a pre 67 body on a post 66 frame w/o doing any mods other than cutting the frame horns off (they installed a crude roll-pan). While it physically swapped, you could tell things were not square & were binding @ the mounts. I preferred an OE/professional look for my swap & opted to relocated & change things as necessary.

For the 5-lug swap, I would get replacement axles in for the 5-lug pattern if you know your current rear end is decent. The axle swap is fairly easy (especially vs swapping another housing into place) & you'll have 100% new, zero bearing wear, stronger than OE axles vs. 30yr old axles. Then just get some 71-72 drums from your local parts store.

I have the 2 frames side by side and see the differences along with the similarities.
I am using an old LWB frame for all of the donor parts (cross members, supports etc.) and as a template for hole placement etc. etc..
I think it will be worth the trouble in the end.
I will also be boxing a good portion of the frame as the torque from the motor I am using will be a factor. I don't want a roll cage if I can avoid it.
Your link to your build didn't work. I'll look for it.