BEST SUGGESTION IS TO USE RTV SILICONE WITH A SEAL A SNUG THEM REAL GOOD
remove the diff cover and let the fluid drain out into a pan. clean the mating surfaces on the both the diff and the cover. use gasket sealer (or proper gasket) on the cover and replace the cover, torque to spec. unbolt the filler cover located on the either the diff or the cover itself. stick the gear oil nozzle in the hole and fill until fluid starts to overflow from the filler hole. replace the filler bolt. you need to know if the rear end has a posi in it. GM posi units require a special additive.
your local jeep dealer should know this just bring in your VIN and they can bring up your vehicles specs
put a drain pan under the diff, unbolt the diff cover and pry it loose, oil will come out. clean out the debris from the cover, put it back, fill diff thru fill hole on cover until oil starts to come out of the hole. put cover bolt back in place. be sure to torques bolts to spec and to tighten the diff bolts in the proper order to avoid warping the cover.
Usually there is a fill only & have to remove the cover. When you reinstall just fill to bottom of hole. Plug on cover or top of "pumkin".You need a diff cover gasket & gear oil of course. It's tricky getting a good seal so use a torque wrench & criss cross when the time comes.
bolt diff cap what is it
It would have 3.73 gears in it
Remove the diff cover.
there is an oil filler plug/bolt located on the diff cover. open it up, put oil in until it starts to spill out, put the plug back in.
THE METAL TAG ON THE DIFF COVER BOLT WILL TELL YOU IF IT IS A POSI OR OPEN DIFF.
Can be found in service manual, possibly at library or at parts store.
It is a chyrsler 9.25, has a diff cover that looks like a stop sign(octagon) and has 12 diff. cover bolts.
get a half inch driver socket wrench, locate the drain plug on the diff. drain plug will be close to the bottom of diff or if there is no drain bolt you must remove entire diff cover, probably 10 bolts. drain, replace gasket or make new one with RTV torque bolts to "gut-n-tight" German standards and fill with new oil at fill plug(upper part of diff cover). recycle oil then take a shower because you probably got some nasty smelling 80-90w on your skin. Done.