I'm planning on putting my '82 Trans Am up on blocks to undercoat the new underbody, so I figured I'd do a little rearend maintenance.

First things first, I would need to change the differential oil. What brand/weight oil do you guys recommend. I heard not to use synthetic because of possible leaking, but other than that I have no idea.

Also, I'd like to check all the bearings, teeth, bushings, and other crap that might be known to fail, along with (trying to) align the driveshaft.

I got a Chilton Firebird shop manual in the garage, but it's too cold to go dig around for it, and I doubt it would be much help anyways.

I can't really afford a new rearend or a rebuild. I can only replace cheaper parts and scrounge around in the local yard for whatever else I might need (in 10 degrees and 2 ft. of snow).

Anyone out there experienced enough with this kind of work to help me out?

 

80 90w gear oil is what you should use. You could use thicker but it just depends on the duty you rear end will see. Synthetic is fine for use in the rear end, if it's not leaking now good chance it wont just by changing the gear oil, I never changed any of my seals from the 3.42 junk yard swap and it has never leaked a drop with M1 gear oil.

 

i've switched everything i have to m1 or amsoil and have never had any problems with leaks.