Its a 88 Firebird formula with the 305TPI F motor and manual trans. At times I here rattling under the car especially when turning to a stop. I lifting the back end up and when rotate the wheels there seems to be alot of backlash. Everything else was fine so it must be the rearend. I have never had one apart. What needs to be done and is a job simple job or a major plan in the butt.

Do you have limited slip? If so, you might want to make sure you have some limited slip additive.

Does this noise when you turn to stop only happen after the car has been driven for a while?

Probably caused by the crush sleeve crushing down smaller and losing preload on the pinion bearing and letting the pinion gear walking up the ring gear. Need to have the crush sleeve replaced with a solid bearing spacer preferably or at least a new crush sleeve.