Differential Service
 

2001 F250 4x4 manual, 7.3


looking to change out fluid in the front and rear differentials as well as the transfer case,
what do you guys recommend?

Easy cheesey. Just use recommended fluids. Nothing special about it, since you're smart enough to be concerned about it, most people aren't.

http://www.guzzle7pt3.com/index.php

Try this buddy. It will help.