Alrighty... I just replaced the fluid in my front diff, rear diff, and the transfer case.... and took a few pictures.
If anyone would like to see how I did it, read on.
(moderators, if this is in the wrong section, I humbly apologize)
Again, vehicle is a 2004 Escalade AWD, with 44,000 miles on it.
Before we start, let's note that I drove the front of the Escalade onto a set of ramps, and then jacked up the rear by the trailer hitch, and placed 2 jack stands under the rear area, to put the truck up in the air and level. I'm not that small, and I was able to crawl around under there with no problems.
Let's start with the front differential:
This is the drivers side of your front diff. Camera is being held near the drivers side front tire, shooting towards the passenger front tire.. looking across the front axle area, if you will.
You see two bolts there. The top one is bigger, it's a 15mm bolt. That is your FILL plug. The bottom one, the smaller one, is your DRAIN plug.
Always remove the FILL plug first, as shown here. (Don't drain it and find out the fill is stuck... that's no good.)
Fill plug is out, came out no problem. Now we remove the drain plug with a 13mm wrench. You're going to have your pan ready underneath this, because when this comes out, fluid will be draining.... the fluid will be shooting towards you a little, so factor that in your pan placement...
Fluid is draining... nice. So far, so good.
That drain plug is a magnetic plug, and hopefully you can see, there is a lot of material stuck on there....
Drain plug wiped off... lotsa stuff there. Hopefully, I did this in time. Honestly, if I had an Escalade with 25k or more miles, I would go downstairs and change that front diff fluid RIGHT NOW. Now. You're still sitting there.... get moving! Joking. Okay, moving along.... let's assume the draining is complete. Replace your drain plug, the 13mm magnetic one.
This is what we're going to use to refill the case. It's a little pumper, I have placed the correct length of hose on the pickup side, to go into a Mobil 1 75w90 bottle... I will put the long hose into the fill hole, and them pump the thing until fluid starts coming out the fill hole, indicating that the case is full to the plug hole... I've had that pump forever, I believe I initially purchased it at a marine dealer, and used it to fill up lower unit gear cases on outboard motors...
Like so. Ready to go.
Here we see I have started pumping, the fluid is flowing up the hose and into the case.
When it's full, replace the FILL bolt, the 15mm one, and you're done.
It took me around 2.5 quarts of 75w90 to fill it back up. An approximate number, there is probably some slight line loss with my long fill tube...
You're done with the front diff!! Congrats! Light a Marlboro, take a break, and get ready to move to the middle of the truck, down the centerline, behind the transmission.
Here we have the Transfer Case. This picture is shot from the rear of the truck, looking towards the front. Thus, this face of the case you are looking at faces the back of the truck. You see the two bolts there. It may not show up on the picture, but this case is actually inscribed "Drain" and "Fill". Same concept as before.
Now, you see the square holes there, and you're thinking "What size wrench is that??" Heh heh, good question.
There's your standard 3/8ths inch socket wrench, with no socket on it. Guess what?? That's the right size square.
Like so. Note that's the drain bolt... we're going to do the fill bolt first, as always.
Fill bolt is out. Case was really full, some came out. I was told at the Cadillac Dealer that that case is full of Auto-Trak II, the blue stuff. Which is $16 a quart. The factory fill, as you can see here, is ATF, Dexron III. So, save yourself some big cash, and just refill it with Dexron III (or Dexron VI) at a far lower price.
This is thinner fluid, so it will really gush when you pull the drain bolt, and it will be coming AT you, so watch it, and watch your pan placement, unless you want a faceful....
I'm sure you've got the idea here, Pull the drain bolt, let it drain, replace the drain bolt, set up your pumper, fill thru the fill hole until it comes out, replace fill bolt... These 2 bolts, like the front diff, came in & out with no problem.
This case took about 1.5 quarts to refill....
Pat yourself on the back, you have now completed 2 of the three cases!!
I've hit the picture limit, seperate post for the rear diff....
If there are mistakes here, I'm sure smarter people than me will point them out. You can save a pile of money here, with some easy work. Hope this helps someone... enjoy.
Re: Front Diff, Transfer Case, how to change fluid. 
