first advice would be to post pics of the axles so that people can tell you which diffs you have.
Second get a bottle of gear oil, a pump--cheap $5 plastic is fine---a good RTV type sealant, a small putty knife, catch pan for oil, can of brake cleaner, grab your basic socket set/ and a couple open end wrenches.
Pull drain plug. Remove cover. Clean all old sealant with putty knife from both surfaces. than clean the inside of axle with brake cleaner wipe clean (oops forgot rags) than clean both surface that get the sealant with the brake cleaner. If (in an extreme case) there is rust or uneven surface on the 2 contact surfaces, clean with very fine sand paper. Be sure to clean again with brake cleaner.
Apply sealant to one side of contact surface (either cover or pumpkin) and reinstall tighten bolts evenly but firmly. I would use a quarter inch drive socket set. no need to over-tighten, if it leaks would follow up with a three eights. DO NOT use 1/2 drive to large a tool this application.
Fill oil in drain plug hole till it begins to come back out. put plug back in. YOU ARE DONE!! and good for another 24K ( I think that is the interval on the TJs.) Easy to do and worst part is the smell of old fluid.