Rear Differential Size?

[Jason in DLH]

So I’m trying to figure out what size rear diff I have. Can anyone confirm that it’s a 8.6” 10 bolt? I know it’s a 10 bolt, but I’m not sure where I need to measure.

Apparently I can find this in the RPO codes, but I’m lost...

Here’s a list of what the codes mean, but still can’t find rear diff size...

http://www.denalitrucks.com/documents/new/2007 YD printbook.pdf

I’ve got a 2007 GMC Yukon Denali.

 

[Just Fishing]

i'm curious on this as well.
I see a GU6 on your sticker, i have that one as well.
GU6 AXLE,REAR,3.42 RATIO

Eventually when i rebuild my rear end, i really want a limited slip or locker of some type...
I did see on my front axle when i had it out for the oil pickup tube o-ring job, it had a "8.25" sticker on it

 

[OR VietVet]

The GU6 is the 3.42 gears and the G80 means it has a limited slip. It is the 8.6 rear axle.

 

[Jason in DLH]

The Denali has an OEM limited slip which I’m very thankful for. The truck is a beast in the snow. Not sure why they simply didn’t add it to all versions.

 

[Just Fishing]

I have the same but lack the G80 option, is it still the same ring gear size?

 

[OR VietVet]

Yes, the size is the same at 8.6.

 

[Just Fishing]

The Denali has an OEM limited slip which I’m very thankful for. The truck is a beast in the snow. Not sure why they simply didn’t add it to all versions.

Really the only thing my tahoe was missing that i wanted, the G80.
My S10 has it (ZR2 package), Over the years i have become a huge fan.

 

[OR VietVet]

Unless you like clacking noises, the full on locker is a bit much but the limited slip does the trick.

I used to do extreme off roading and had a 73 Blazer with a one ton 14 bolt in the rear and a 1 ton Dane 60 in the front and both had 4.88 gears with Detroit Lockers in them. Yes, lots of clacking noise when really working it over rocks or some extreme trails.

 

[Jason in DLH]

The GU6 is the 3.42 gears and the G80 means it has a limited slip. It is the 8.6 rear axle.

Great, thanks! Mine is all rusted (got WD40 rust *********** spray soaking in the bolts now) and plan to replace it with a new gasket, bolts, and cover.

 

[OR VietVet]

No problem. Make sure the surfaces are completely clean and dry when put back together and just use a very thin film of sealer on both sides of the quality gasket on reassembly. I like to let sit for about 1 hour after installing bolts, before I refill the diff.

 

[Just Fishing]

Unless you like clacking noises, the full on locker is a bit much but the limited slip does the trick.

I used to do extreme off roading and had a 73 Blazer with a one ton 14 bolt in the rear and a 1 ton Dane 60 in the front and both had 4.88 gears with Detroit Lockers in them. Yes, lots of clacking noise when really working it over rocks or some extreme trails.

Off roading that S10, i ended up in some pretty tough spots.
My first real experience with that G80 was a pretty loud ratcheting sound coming from the rear end, and the truck continuing to move up a very steep rocky hill.

From what i was told, even though it's a "G80" it's not a limited slip but a locking diff.
I would be very happy with the same config as my old S10.

Only weird thing i ever had with it was a hard U turn in AZ @ 119F
locker kicked in and i ended up going onto the curb.

 

[Jason in DLH]

Whoops! Reminds me of a time when I tried to do a power slide in my ‘05 Ram and didn’t work as well as I thought it would and ended up driving over the center curb. Whoops!

 

[Jason in DLH]

Strangely enough my mishap was in AZ as well. Must be their streets down there.

 

[Just Fishing]

Also the rear diff on my 09 had a rubber/metal clad gasket.
I had the standard gasket ready to rock, but the OEM gasket was still on good condition so i rocked that.

Just something to watch out for, might save your self a few bucks.

I also see the diff cover bolts torque spec (While I had my service manual out)
30 N·m (20 lb ft).

 

[Just Fishing]

Strangely enough my mishap was in AZ as well. Must be their streets down there.

I blamed the heat @ 119F
The heat also warped the dashboard...

 

[Jason in DLH]

No problem. Make sure the surfaces are completely clean and dry when put back together and just use a very thin film of sealer on both sides of the quality gasket on reassembly. I like to let sit for about 1 hour after installing bolts, before I refill the diff.

I plan to use RTV in place of a gasket. And plan to clean it thoroughly. I’m actually going to clean the diff off really well before opening it up as I don’t want anything getting into the gears. I’ve seen people put aluminum foil in after they take the cover off.

 

[Jason in DLH]

Also the rear diff on my 09 had a rubber/metal clad gasket.
I had the standard gasket ready to rock, but the OEM gasket was still on good condition so i rocked that.

Just something to watch out for, might save your self a few bucks.

I also see the diff cover bolts torque spec (While I had my service manual out)
30 N·m (20 lb ft).

great, thanks! That was something I was looking into. I got the specs on the drain/fill plug at 24 lb ft.

 

[Jason in DLH]

Also the rear diff on my 09 had a rubber/metal clad gasket.
I had the standard gasket ready to rock, but the OEM gasket was still on good condition so i rocked that.

Just something to watch out for, might save your self a few bucks.

I also see the diff cover bolts torque spec (While I had my service manual out)
30 N·m (20 lb ft).

I was just closing my Haynes info and saw that my cover bolts should be at 30 lb ft.

 

[Just Fishing]

I was just closing my Haynes info and saw that my cover bolts should be at 30 lb ft.

View attachment 261352

Weird, maybe it's an 09 thing.
But that was a copy paste from the factory service manual.

 

[Just Fishing]

My FSM covers 07 as well, so i changed the year.
yup 30 for the 07!