Hello everyone,
I just came across this forum and it seems to be a wealth of information here. So I decided to join and saying hello with a few questions as well.

I have a 1968 4x4 short bed that has a SM465 tranny, and a NP205 transfer case. The engine is just a small 283 (will update that eventually). The body on the truck is great, but since it came from the north the entire undercarraige is full of rust. I would like to update to a newer frame and suspension, pretty much just put the 68 body on a new frame with all of the suspension, front and rear ends.

What years is this possible with, if it even is? I've searched and found that 60-87 front ends are interchangeable, but what about the rear? Any help would be greatly appreciated.  

Well for certain any 67 - 72 will swap out easy. I am unsure about the 60-66 and 73-87 frames.  

The beds bolt on the same up to 87. The cab mounts are different in the series trucks. I have a 55GMC on a 72 c-10 chassis. Bed bolted on like its supposed to, and made/refabbed cab mounts.  

60 to72 all had the same coil rears but 73-87 had leaf springs but you can still put a later rear in with CCP spring perches. Just weld them on the same as the old rear