Rear End Gear 96 LT

I am wanting to change the fluid in my rear diff and the gasket. Since the rear has a couple different gears how can I tell which is the correct gasket since the local AZ carries two different gaskets? Also wanting to replace all the bump stops. WHat type would be the best to use?

I think the rearend ratio is stamped on the front side of the passenger side axle tube. Sorry, I don't know about the bump stops.

Most rear ends have a id tag on back of cover bolt.
Some Rear ends size's are ID by the no of bolts in the cover.
The rear end size not gear ratio tells what gasket to use.

If you need new bumpers your dealer should be able to get them for you.