im doing a rear diff swap on my girlfriends 2003 explorer limited with advancetrac, 3.73s, and limited slip. the pinion bearing has been gone on it for a while and the rear diff has been whining under load. I got a rear for it, with a 90 day guarantee. the questions I have may be answered during the disassembly process of her car but for now I just got a few questions before I start. ive done axle swaps in the past, but solid axles, and the only diff ive changed just a pumpkin was a GM 9.5 IFS. I just want to know how im going to swap the spindles over, it looks like they just go in on splines, but Im wondering if theres a snap ring, or what holds them in place. also, does the rear diff cover have a gasket when I split the case, or is it just RTV, I haven't taken her car apart yet or given a second look to the diff I have, its oil covered, but it was from a junkyard, so Im not sure if theres a leak or its other oil or what. however, im going to split the case and re-seal it. if anyone has done this before, or has an pointers or anything let me know. thanks a lot.

 

The rear knuckles are mounted with upper and lower bolts thru a rubber bushing. You take out the upper bolt, take off the axle half shaft nut, and fold the knuckle down horizontal as you push the axle shaft out of the splines. When the knuckle is out of the way, you have the axle half shaft just hanging there with the CV joint / boot visible at the outer end. Prop it up with a 2 x 4 about 6 inches long laying on the knuckle so the shaft stays about horizontal. Take a 2 x 2 about 12 inches long and crawl under the backend of the truck with a 5 pound hammer. Uses the 2 x 2 as a punch and set it against the half shaft about 2-3 inches from the differential. Whack the 2 x 2 outward toward the tire and the half shaft will "pop" out. It has a spring retainer that drags on the housing to keep it in place... no snap ring. One side is 1 inch longer than the other, don't get them mixed up during reinstall. After the half shafts are both out, you drop the drive shaft U joint, then about 3 or 4 large bolts that rubber mount the differential to the frame. lower with a 1/2 ton floor jack. Once it is out, you can take the rear cover off just like a normal rear end.......... except all is aluminum.

 

https://www.ford-trucks.com/forums/1...e-rebuild.html

 

Leaks can be the rear pan cover... or more likely the seal on each side where the half shaft pokes into the housing.