"1950 Chevy 3100 with a 235 followed by a manual 4-speed tranny that has a torque tube driveshaft going out back to a set of 4.11's"

"I appreciate all the great advice, but never really got an answer to my original question."

Questions:

1. "Can anyone tell me if I can change the torque tube driveshaft and the rear end to one from say a 55-57 Chevy truck or car? "

2. "Will the driveshaft & rear end from a 54-57 car or truck be a direct bolt in to the 50?"

Short answers:

1.Yes, you can change anything if you have the time, $$$, and expertise.

2. No - not a direct bolt in (except perhaps from a 1954 Chevrolet/GMC 1/2 ton truck)?

There most likely are no other simple answer? But, it would nice to be wrong.

Many people here have done many conversions, most of which most likely require non-simple descriptions?