Does anyone have a how to on differential and transfer case?

I was looking to do the front/rear differentials along with the transfer case on my wife’s 2008 Yukon Denali. I was looking for capacities and verification on the fluids. Also do the differentials have gaskets or can I just use permatex? Would this vehicle be considered a 2500 or a 1500, because they have two different types of front axle fluid listed. And is the rear a posi? Would I need additive for this?

Here is what I have so far:
Front Axel (for 2500 series vehicle):
SAE 75W-90 (SAE 80W-90 for 1500 series)
Synthetic Axle Lubricant
Capacity???
Torque for cover???
1500 or 2500???

Rear Axel:
SAE 75W-90
Synthetic Axle Lubricant
Capacity???
Torque for cover???
Posi???

Transfer Case Fluid:
2.0 qts.
DEXRON®-VI Automatic Transmission Fluid.

http://www.extendedgmwarranty.com/owners-manual/gmc/2008-GMC-Yukon-XL.pdf

If the truck is a Yukon, pretty good chance it is the 1500 specs. The Yukon XL was available in both 1500 and 2500. Also, you may want to use GM Auto-Trac Fluid in the Transfer Case, so as to not have any issues with chatter.

Donnyballgame said:

If the truck is a Yukon, pretty good chance it is the 1500 specs. The Yukon XL was available in both 1500 and 2500. Also, you may want to use GM Auto-Trac Fluid in the Transfer Case, so as to not have any issues with chatter.

Click to expand...

Auto-Trac fluid in the transfer case? So the transfer case uses clutches?

If your 4wd selector on the dash has an Auto setting, then yes, there is a clutch in your transfer case.

Donnyballgame said:

If your 4wd selector on the dash has an Auto setting, then yes, there is a clutch in your transfer case.

Click to expand...

I have no selector on the dash.

OK, so I am not sure, but think your Denali is AWD. I will let somebody else try to help and verify that for sure.

It's a 1500 and it's all wheel drive (most likely, they are offered in 2WD but are VERY rare). There is a 2500 version of the Yukon XL but they aren't offered in a Denali trim.

Here's the tech specs from Autobook (program we use to build rigs for factory orders from GM). It's for a 2011 but the drivetrain is the same for all the 2007+ NNBS Yukon Denalis.

2011 Retail GMC Yukon AWD 4dr 1500 Denali TK10706
TECHNICAL SPECIFICATIONS
POWERTRAIN - ADVANCED SPECIFICATIONS - 2011 Retail TK10706 AWD 4dr 1500 Denali

TRANSMISSION
Gear Ratio 1)
First Gear Ratio 1) 4.03
Second Gear Ratio 1) 2.36
Third Gear Ratio 1) 1.53
Fourth Gear Ratio 1) 1.15
Fifth Gear Ratio 1) 0.85
Sixth Gear Ratio 1) 0.67
Reverse Ratio 1) 3.06
Clutch size (in)
Power Take-Off
TRANSFER CASE
Transfer case model Magna
Gear Ratio 1)
Transfer case high gear ratio 1.00
Transfer case low gear ratio
Transfer case power take off
DIFFERENTIAL Front Rear
Axle Ratio 1) * 3.42 * 3.42
 

2011 Retail GMC Yukon AWD 4dr 1500 Denali TK10706
TECHNICAL SPECIFICATIONS
PAYLOAD/TRAILERING SPECIFICATIONS - 2011 Retail TK10706 AWD 4dr 1500 Denali

WEIGHT INFORMATION Front Rear Total
Gross Axle Wt Rating (lbs) 3,600.00 4,100.00
Curb Weight (lbs) 3,088.00 2,806.00 5,894.00
Total Option Weight (lbs) * -66.00 * -11.00 * -77.00
As Spec'd Curb Weight (lbs) * 3,022.00 * 2,795.00 * 5,817.00
As spec'd payload (lbs) * 1,483.00
Total Weight (lbs) * 3,022.00 * 2,795.00 * 6,167.00
Reserve Axle Capacity (lbs) * 578.00 * 1,305.00 * 1,883.00
Gross Vehicle Wt Rating (lbs) 7,300.00
Gross Combined Wt Rating (lbs) 14,000.00
TRAILERING Max Trailer Wt. Max Tongue Load
Dead Weight Hitch (lbs) * 5,000.00 * 500.00
Weight Distributing Hitch (lbs) * 7,883.00 * 945.96

I'm pretty sure the rear diff has a limited slip unit but the front is open (they have an active wheel braking system though so if one slips it'll apply braking to it to allow power to transfer to the other side, so it kind of acts like a limited slip).
I don't think any special additive is needed. GM did come out with a special additive for their limited slips that supposedly reduces clutch slippage in the LSD, but it was mainly used to quiet a noisy Diff. Some guys put it in the trucks which have lockers to eliminate the "chatter" around corners but from what I understand it effectively turns it into an open rear. It won't hurt anything and I don't think it's expensive so I'd probably just throw some in if you are changing the fluid anyway.

---------- Post added at 04:12 PM ---------- Previous post was at 03:56 PM ----------

Here's some more info from GM SI:

Application
Type of Material
GM Part Number

Differential Carrier Assembly Case Mating Surfaces
Sealant
1052943

Electric Motor Actuator
Sealant
12346004

Front Drive Axle Bearing Adjusters
Lubricant
1051344

Front Drive Axle (8.25” S4WD Axle)
SAE 80W–90 GL5 Lubricant
89021671

Front Drive Axle (8.25” F4WD Axle )
Synthetic Gear Oil
89021677

Front Drive Axle (9.25” Axle )
Synthetic Gear Oil
89021677

Front Drive Axle Inner Shaft Housing to Differential Carrier Assembly
Sealant
1052943

Pinion Yoke Splines
Sealant
12346004

Rear Axle:
SAE 75W-90 Synthetic Axle Lubricant GM P/N 89021677

Thanks! And it does have a posi, I found it on the window sticker, so I'll use additive.
Is the Transfer Case Fluid 2.0 qts. DEXRON®-VI Automatic Transmission Fluid correct? With no additive? What transfer case would it have? The casting says Borgwarner AZ91D.

Yep thats the right fluid, and no additive. I think it takes 2.2 qts or something, so I'd get 3 qts just to make sure you don't run out and have to make a parts run during the job. The service info says to fill it up until fluid starts coming out of the fill plug (about halfway up the t-case on the same side as the drain plug). The transfer case should be the borg warner 4885-NR3

Thanks!