Change the fluid in it, and use the GM limited slip additive.
If you want to get fancy you could go synthetic, but not necessay
if you're on a budget. Make sure you have the right drive shaft.
If I remember correctly, you had a 7.5" read in the car. The
drive shaft with the 7.5" is approx. 1 inch longer than the shaft thats
used with the 8.5". If you're changing the rear suspension, the UMI
parts advertised here seem to be of good quality for a very fair price.