I'm in the process of putting the LSD on my 83 back together but I only have access to an 85 FSM. Are there any differences between the 83 and 85 in terms of backlash, torque specs, friction plate specs and so forth? Could I use the info from the 85 manual?

 

I have a shop manual for 1980 and a haynes(junk).
there isn't much difference between the numbers go with what your book has printed.

 

I've got two books a haynes (junk) and a shop manual.
both however do have the same numbers for setting the rear.