Here are some random thoughts on differences from the back to the firewall?
The tailgate for the 72 has the backup lights, not in the bumper.
I think the door lock knobs are in different places for the 72 and therefore that may effect door panels.
The electric harness will likely have some differences.
The dash, gauges, AC and heating, vents/controls will likely have differences.
The key is on the column for the '72 and I think the dash for the '68.
I'll be moving pretty much everything over, dash, column, new wiring, gate etc... I just want to be sure that the parts will bolt on and that there's no big differences in frames, bodies, suspension etc... Thanks for the response!
The frame is the same. Its the GM Heavy Duty #1942 unit. They only used that frame on 68-72 el Caminos and the 69-72 Pontiac Grand Prix.. John DeLoran wanted his baby to have the best frame available from GM at the time.. I'll never forget driving a 69 GP w/ 428-4 speed for the first time, WOW what a car!! That frame is why the 68-72 el Camino rides and handles like it does.