hello all,
New member here with a question that may have been answered already. I have been searching the threads and found lots of good info that has helped me but nothing definitive. I am trying to make one good cab out of two compromised ones. I have a 46 1/2 ton which is original to the truck and what I believe to be a 40 cab that was bought as the donor cab. As it turns out the donor cab is in better shape than the 46... so.... I want to make a 46 cab using most of the 40 cab. I believe the two major differences between these years are the firewall extension and rear window mounting. I also believe that the fender attachment will have to be dealt with. There are other small differences that I think will just require using different fasteners.
My plan is to cut out the firewall extension and rear window of the 46 and weld them into the 40 cab. if anyone has any thoughts or has tried this or anything similar any help would be appreciated.

Attached Images
2cabs.jpeg 46halfton.jpeg