for the same year I think you'll find some differences Chev vs GMC around the front crossmember, as the GMC had a different engine mount setup ... between 1/2 and 3/4 there will be different springing, so maybe different mount points

if you've got both at hand, just put'em side by each and start comparing, with your plans in mind re winding up with a 1/2 or 3/4 and what engine you'll use

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics