ok this is how to change your differential fluid in the rear end of your trucks. Let me start by saying you will get lubricant on the floor. It's unavoidable. If you have been driving your car for any length of time, the lube will be hot, so please be careful and have the oil soak and shop towels handy. Also chock the wheels if you aren't using a lift, and leave the transmission in neutral. Remember to always use automotive jack stands rated to withstand the weight of your car.
Begin by orienting the gasket with the bolts, making sure it is the CORRECT gasket. Next, remove the bolts that hold the backing plate. Notice that there are 2 brackets that also use these bolts. They anchor the brake lines. These bolts are slightly longer than the others, so pay attention to this during reassembly. As soon as you get the bolts out of the bottom, you should begin to see some dripping, so be sure to have the drain pan ready. When all the bolts are out, gently pry or tap the backing plate to get it off. Hang on to it, or it'll wind up in your drain pan. The lubricant should flow out of the housing rather quickly and with a big splash. If you use any oil soak, keep the dust to a minimum as it will get inside your differential housing.
Now its time to clean everything. Most people agree that using your hand to try to wipe off as much of the old lubricant as possible is good enough. There is nothing wrong with leaving a residue of old oil on the gears. I then use paper towels to wipe out all the material from the bottom of the housing. Although you don't have to worry about getting all the old oil out, make sure you get all the old metal shavings out.
Notice what looks like a big washer attached to the plate? That's a magnet and is glued to the plate. Don't try and remove it. Make sure the old gasket is COMPLETELY removed from both the housing and backing plate. Depending on the age and condition of the old gasket you may have to use a razorblade to remove any excess gasket that is stuck.
Put 2 bolts into the backing plate, 1 on each lower side (remember the magnet goes down) and carefully replace the backing plate. Remember the 2 longer bolts go with the brake line brackets and the backing plate is notched to accommodate them. Be careful not to over tighten the bolts.
Use a 3/8 inch drive ratchet to remove the fill/level check plug on the right front of the differential housing. Add the additive first and then fill with the lubricant. This can be tricky, messy and frustrating. I used a small funnel with a clear tube attached so that I could see the lube flowing. You will know its full when you see the oil reaching the top of the fill hole. Once full, replace the plug and you are finished.
I suggest you drive slowly for a couple of miles, allowing the additive and lubricant to mix thoroughly. Stop and check for leaks and after a few miles check the differential level again.
Try using a squeeze bottle with a long nipple to add the fluid. You can pour the additive into the bottle along with the fluid and shake them until mixed. Then use a section of clear motorcycle gas line clamped over the nipple to stick into the rear differential fill hole. This filling method saves a lot of spills and keeps your blood pressure within safe levels.
Hope that this helps. I did this on my 99 last weekend. I should have taken pics, but I did not want to get the camera messy. If you have any Questions then please post them. It should be the same for most year models.
Phiber-Optik
