Can I directly bolt on a '77 1 ton cab to a '73 1/2 ton frame?

[seventyx3]

I want to replace my cab due to rust.  The old one has gone to scrap.  I know a 3/4 ton should be a direct bolt with frame specific mounts, but what about a 1 ton cab?  While I'm on the subject, will an 81-87 era cab bolt directly to a 73 frame?   Can anyone refer me to threads with rust repair on the windshield lip or firewall?  You would think I could find a great cab in AZ but I'm  O for 3. 

[Blazin]

All the cabs are the same as far as mounting them to the frame. The actual body mounts go from 73-80 and 81-87. You will need the mounts that are year specific to your frame. You neglected to mention wether yours or the donor is 2 wheel or 4 wheel drive. 2 wheel drive 3 speeds, and automatics had a low center hump. SM456 2 wheel drives had a tall hump. All 4x4s had a tall hump.

[seventyx3]

Everything is 2wd auto -TH350.  So technically, I could bolt an 81-87 1/2, 3/4, or full ton cab on a 73 1/2 ton frame as long as I use 73 1/2 ton cab mounts? A 73-80 front clip will bolt on an 81-87 cab without issues, but not vice versa, right? 

[Blazin]

Correct, there is no difference in cabs as far as GVW goes. You will need to swap in the 73-80 Wiper stubs, or entire transmission assembly as the 81-87 stubs are to tall for the hood to clear. One of the three holes on each stub line up. The other two on each stub are off about half a hole. A little work with a chain saw file fixes it though!