It's not difficult to do if you have any expierence with rear ends, and no you don't need a compressor. Just pull the axles, and take the diff out of the housing. Now take out the "S" shaped spring, spider and side gears, and clutch plates. Just put it back together with the new plates and ya got it. Hardest part is usually getting the spring back in.
------------------
1985 Mustang GT
'85 GT 13.20 @ 105.8 / '72 Mach1
Long list...check website!!
My Website