The adjustment can be done fairly easily by an experienced person. In my case I had to do a lot of reading first. Trial and error.

Starting page 29:
http://chevy.oldcarmanualproject.com/booklets/52mts12/5212mts00.htm

Starting page 29:
http://chevy.oldcarmanualproject.com/booklets/55top06/index.htm

Tech tips:
https://www.stovebolt.com/techtips/axles/355%20gear%20swap/

Pictures and write-up are not mine.
Attachments
Rear Axle 01.jpg (47.43 KB, 90 downloads)
Rear Axle 02.jpg (66.68 KB, 90 downloads)
Rear Axle 03.jpg (79.86 KB, 90 downloads)
Rear Axle 04.jpg (20.51 KB, 90 downloads)


"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."