Have you noticed a oil leak when doing a brake job? dont let it ruin the shoes and affect braking ability, the risk of running the differential low on oil, and the mess you'll have the longer you let this problem go. I started with blocking the front tires, there will be times to have the transmission in netrual and time you will want it in park or 1st (depending on trans type) after blocking the tires, slide a pan under the rear differential and remove cover bolts, crack the cover loose so the oil starts draining out. while its draining, take off both back tires, place jackstands under the axlehousing at each side and remove brake drums. place floor jack and blocks under rear bumper (receiver hitch if you have one) jack up body about 2-3 inches to give yourself some working room, but not so much that your off the jackstands. remove rear cover completely. you will now want the transmission in netrual. rotate the ring gear until you can see the retaining bolt for the cross pin.
when it is directly in the middle, cross pin level, go put the trans in park or 1st gear to hold the driveshaft-ring/pinion in place. the cross pin retaining bolt is a 5/16 hex head, it is in tight and with loctite from the factory, get a 5/16 wrench with a 6-point box end and put on the bolt, tap with a hammer to break it free.
once you remove the retaining pin, go put the transmission back in netraul so the carrier will move, turn the carrier and the cross pin should slide out.
once the cross pin is out, push each axleshaft in one at a time and remove the "C" clip retainers.
i used a magnet, needle nose pliers will work also. once the "C" retainer clips are out, the axleshafts can be removed.
before you pull the axleshafts out, put a shallow tray, like the top off a gallon ice cream tub under each brake assy, this will catch any oil that is still in the axle tube, and when you spray brakeclean later it will catch that nasty mess. remove axles and slide them into the back of the bed. the driver side shaft is longer than the passenger side by about 2".
(I didnt measure, but its a noticeable difference) remove the old seals, sure you may only have one leaking, but do both, youre here anyways, its only $4.00 per seal and you shouldnt have to do this again any time soon. I use a seal puller from sears,its kind of like a prybar with curved sharpened ends, its about 10-12 bucks, alot easier than trying to use a screwdriver.
once the seals are out, stuff a small rag into each bearing and spray the heck out of your brake assy's with brakeclean.
since youre doing this job probly because you have a bad seal, this is the time to get all the nasty mix of hypoid oil and brake dust removed.
mine was leaking just bad enough to run down the inside of the backplate, wasnt soaking the brake shoes yet. if yours has gotton that bad you may want to put new brakes on.
also clean the axles at the wheel flange end, use a little scotchbrite where the seal/bearing rides.
next compare your seals, I was given the wrong ones and had to go back, even though I gave the correct information, it happens, this is one of those times youre not sure you have the correct part until its time to reasemble.
when your sure of your seals, gently tap into the bore. I dont have a socket big enough to use as a driver, ive used a small 2x4 block before, but ive done enough seals that I just usually tap back and forth then work my way around the seal until its flush with the housing. this is no place to rush.
once the seal is in, take some light grease and coat the inside lips of the seal.
I also coat the axleshaft where the bearing/seal area is. next slide the axleshafts back in.
there is a small o-ring there where the retaining clip goes, not sure why ford does this, g.m. uses a similar retention design but no o-ring.
push the axleshaft all the way in, slide a clip onto the axle are where it goes, then move the axleshaft back out to seat the clip within the side gears. spray the threads of the cross pin retaining bolt and the threads where it goes in the carrier with brakeclean. you may have to move the carrier slightly to line up the carrier with the spider gears, and sometimes the spiders like to move a little when your moving the carrier without the cross pin in place.
once the cross pin is in, slide the retaining bolt in, but dont tighten. put some loctite on the threads before tightening. this is one bolt you do not want coming out! place transmission in park or 1st to hold carrier in place so you can tighten the retaining pin down.
clean up your cover and the mounting face of all silicone or gasket material. wipedown with brakeclean. from the factory alot of these used no cover gasket but just rtv silicone. you can get a gasket if you choose. I have a aftermarket cover and prefer a gasket. after you clean both surfaces, take a break and slide the brake drums back on.
adjust brake shoes if needed (my self adjusters dont work, im sure many others have this issue) use whatever method you wish to seal your cover, rtv or gasket. put cover on and start all the bolts.
the torque for the cover bolts im uncertian of, hanyes book didnt list it, I went online and found various figures anywhere from 15/20 ft pounds to 25/35 ft pounds. i would think the lower figure is for the composite cover, the higher for a steel cover. I went with 25 ft pounds myself. remember to tighten it down like you would a tire or cylinder head, go back and forth across the cover to torque it down evenly. next fill the differential with oil, remove the plug and put oil in until its running out. will vary with axle type and mine takes more than it used to because of my cover.
I used a gallon jug of 80w 90 std gear oil from wal-mart. the pump made this very easy to deal with. took a little over half.
it was a little easier with mine due to the design of my rear cover having a rear drain and fill hole. be sure to use limited-slip rated oil if you have a limited slip.
last, put your rear tires back on and tighten accordingly. be sure your in park/first before removing the jack and blocking. with the right parts on hand this isnt too bad a job to tackle.