4 bolt Rear end trouble

[1991GSXAWD]

I recently realized after having the transfer case replaced that my 4 bolt rear is making a high pitch noise especially after it gets hot from highway driving, yes it's full of oil, i was under the car the other day and noticed a lot of excessive play in the rear end(the pinion gear) I'm not into rear ends that is why i'm asking for help, is there anyone that sells rebuilt kits? Or what can i do to fix the problem? Thanks in advance.

 

[DSM90AWD]

I'm not into rear ends that is why i'm asking for help

ummmm..

There is a factory lash limit for the rear differential. For the 1Gs it is 7mm.
Check this THREAD which has a bunch of info on measuring lash and other causes of rear end noise.

Also you may want to check your rear axle bearings as when they wear out you will also hear whinign (and a rumble)

 

[1991GSXAWD]

Thanks for your help, i'll be pulling her apart next week as soon i have the lift installed in my garage, i'm getting tired of working on my back, age will do that to you.