TB Ext 8.6 swap (G80) info

redleg6

Original poster
Member
Apr 10, 2012
686
I've searched on here, on ORTB, and on the other site. I've only seen minimal coverage about an actual swap of a LWB TB rear axle into a LS like mine. I saw where Hardtrailz did the SS rear axle swap, but to me thats not exactly the same.

I have a 4WD 3.42 rear, GU6 option which infers non-locking. I dislike one wheel spinning in soft dirt, hence the desire for a G80.

Found a suitable match on car-part.com, but have not made it to the U-Pull-It (in Liberty, MO) yet to see in person. I'm not anxious about going there in the mud to pull out a sub-400 pound bunch of metal by myself.

I hesitate to call this a build as I prefer to buy everything I need first, block out time and money to install, then test it all out. Yet my plan is still to get the rear axle, do the Ext rear brakes on my LS, and if money prevails, get the lift/suspension on par with what I've seen others do on ORTB. I'll say it now, I'm not a serious off-roader as this is my daily driver, but I do live in a rural area and will need purposeful working 4WD in the future.

I will take photos and write comments as I go on after getting the axle. But would really like to see if anyone else has done this on their TBLS and see if there are any lessons learned I can utilize.
 

jimmyjam

Member
Nov 18, 2011
1,634
i helped swap one on decemberend's ls tb. not much to it, unbolt the old one, bolt in the g80. pulled the g80 at a u-pull, might be tricky to yank it without another set of hands seeing how they don't let you use a jack
 

Conner299

Member
Jan 16, 2013
279
I just recently had one freighted to me. Its weighs approx 226lbs. As far as I know, the rear brakes on SWB and EXT's, are the same. The GU6 refers only to your gearing. Check your glove box production code sticker for the "G80" code. You might want to consider getting one with an open diff(no G80), depending on the vehicle mission. If you plan to do a serious amount of offroading, a locker maybe more beneficial. Also, some don't like the G80 because it has more moving parts than a locker, and can be more prone to breakage.

EDIT: Sorry just saw the part about not doing serious offroading.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR

redleg6

Original poster
Member
Apr 10, 2012
686
the roadie said:
The definitive thread from the OS: forums.trailvoy.com/showthread.php?t=56696]Grenaded Differential - Upgrading to 8.6" LWB...

and here I thought that was all about your blown-up G80...re-read it all and i'm feeling better about doing this at someplace like my dad's garage...might have to use his truck though (axle won't fit in the back seat of my wife's car)

while the axle is off, I should replace springs/shocks and other items...thanks Roadie
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,149
Brighton, CO
DDonnie said:
Correct me if i'm wrong, doesnt the 5.3 swb have an 8.6?

That is correct... OP has a SWB 4.2..
 

dfc739

Member
Jul 29, 2012
170
Des Moines, IA
redleg6 said:
I've searched on here, on ORTB, and on the other site. I've only seen minimal coverage about an actual swap of a LWB TB rear axle into a LS like mine. I saw where Hardtrailz did the SS rear axle swap, but to me thats not exactly the same.

I have a 4WD 3.42 rear, GU6 option which infers non-locking. I dislike one wheel spinning in soft dirt, hence the desire for a G80.

Found a suitable match on car-part.com, but have not made it to the U-Pull-It (in Liberty, MO) yet to see in person. I'm not anxious about going there in the mud to pull out a sub-400 pound bunch of metal by myself.

I hesitate to call this a build as I prefer to buy everything I need first, block out time and money to install, then test it all out. Yet my plan is still to get the rear axle, do the Ext rear brakes on my LS, and if money prevails, get the lift/suspension on par with what I've seen others do on ORTB. I'll say it now, I'm not a serious off-roader as this is my daily driver, but I do live in a rural area and will need purposeful working 4WD in the future.

I will take photos and write comments as I go on after getting the axle. But would really like to see if anyone else has done this on their TBLS and see if there are any lessons learned I can utilize.

As a fellow Kansan, I can tell you that if you spot it at U-Pull-It or U-Pick-It in east KC, you have to get there fast. I periodically check the online inventory and I went to check out a wrecked Trailblazer one weekend. It was only on the lot a week and then it was gone. Luckily I had already pulled the parts I wanted. Also, the truck section of the yards is usually pretty good. Lots of gravel and little mud. It seems like the car sections are more mud/puddles of water. I know they let you rent/borrow carts. PM me if you need a hand. I'm also interested in swapping my 8.0" for an 8.6" but I'll hold off.
 

saabotage

Member
Apr 20, 2013
14
I just swapped an 8.6 out of an xl denali into an 02 swb 4.2 Envoy. The job went flawlessly.......Was worried about the driveshaft from the 02 working in the 8.6 rear end but it went in great. Only difference was the 8.6 had abs and the swb didnt, so i just deleted the harness.
 

DDonnie

Member
Mar 26, 2012
2,631
TollKeeper said:
That is correct... OP has a SWB 4.2..

TY, i was actually wondering for mine :biggrin:
 

redleg6

Original poster
Member
Apr 10, 2012
686
dfc739 said:
As a fellow Kansan, I can tell you that if you spot it at U-Pull-It or U-Pick-It in east KC, you have to get there fast. I periodically check the online inventory and I went to check out a wrecked Trailblazer one weekend. It was only on the lot a week and then it was gone. Luckily I had already pulled the parts I wanted. Also, the truck section of the yards is usually pretty good. Lots of gravel and little mud. It seems like the car sections are more mud/puddles of water. I know they let you rent/borrow carts. PM me if you need a hand. I'm also interested in swapping my 8.0" for an 8.6" but I'll hold off.

sounds like a good plan and thank you

will contact you when I get the axle if youre still up for being on hand for the swap...my dad's place is in Spring Hill
 

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