no gasket, just use a generous bead of rtv to seal the cover. be sure and go around the bolt holes too. use black, because a little will ooze out and orange or blue looks silly. also don't over-torque the little cover bolts. they can't stand a lot, check the manual but maybe 15-20 lbs is all. you should have a rubber plug about 1/2 - 2/3 of the way up the diff cover. fill it to the bottom of that hole. just my opinion but shiny diff covers are a waste of money.

 

The plug is right in the middle of the cover offset to the right of center just a little. It's a rubber plug. That is the fill plug. Once you have the rear cover off, fluid drained, cover cleaned, gasket made of rtv, and cover re-installed, you just fill with fluid until it starts running back out that plug. Mine took just over 2 quarts.

I don't think there is a gasket you can get for the rear cover. Just get some rtv and apply one bead all the way around the middle of the lip of the cover and make a loop of rtv around each of the bolt holes.

One more note, take the spare tire out. Much easier.

 

post update.

bought the tranny sensor and ordered the brake light switch at advance auto parts. many of these parts are now available at your local parts store. changed the speed sensor located at the transmission(cost $16.00). It did not fix the abs and break light problem but I can tell that the transmission is shifting like a million times better. definitely a good move even thought my abs and break light switch is till on. The break light switch will be delivered at the store tomorrow(cost $14.00). Therefore I will install it tomorrow(some people claim that it has solve their problems). As for the differential fluid change I will tackle that job next saturday morning. thanks dhvaughan for your help. It should be preatty easy to fill the differential through that fill hole.

 

installed the brake light switch per the manual. It took about 3 minutes but the lights(abs and brake lights)turned on. I also noticed that the speed sensor on the tranny was leaking trans oil. apperently the new sensor that i bought did not come with a o-ring on the sensor. I removed the o-ring from the old tranny sensor and installed it on the new sensor and on the tranny. to summarize. I have replaced the rear speed sensor, the tranny speed sensor, and the brake light switch. the abs and brake lights still turn on the dashboard. the lightsdo not turn on immeadiately, sometimes they take less or longer. but they do turn on. My next move are to install all new fuses and to change the differential fluid. I don't know if it's worth it to change the abs module. although they are not as expensive as people in these forums say.