[sweet70beast]

I believe that you will have to replace the whole axle because the old one is meant to pivot. The only auto trans that I can think of that came with a bolt on yoke is the TH400(475). Which usually came in the 1 ton and bigger plus in motor homes too.
If you're still using the torque tube I am figuring that you are using the original truck 4 speed, right? That is shorter than a 2004r. If it is the 60's and 70's 4 speed car saginaw than it should be the same length.
If your motor came from a 72 C10 and is a 6 cylinder it could either be a 250 or a 292.