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Discussion Starter #1 (Edited)
3.08 Differential ???

Hi , life is full of mistery.

Last summer i buy a GMC VAN G2500 from the original owner widdow. I was planning to swap the 6.2 engine-th700r4transmission into my pick-up keep the spare parts and throw the body away.

This morning i open the differencial for curiosity to know if it’s worthless and make some room.

It look to be a “ 3.08 limited slip“.:cool: Make it turn and count the turn .

I never hear of that setup on a GMC van . No sing of modification or wedling ,everyting looks original and in good shape to me. Someting special to look for before i upgrade my pick-up with a “brand new second hand differential”
 

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What you have there is a G-80 10 bolt locking differential. Or as some of us call them eaton gov loc;)
 

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Eagle Eyes
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I thought GM didnt put any type of locking differential in the 10 bolt axles because of strength concerns. Big warning in the book not to modify yourself.

I thought only was available in 12bolt and up.

tigman, does it still work?
 

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Discussion Starter #4 (Edited)
eaton gov lock

Hi , D.Camilleri , it is a 9 1/2 inch diameter with 10 bolt patern on the cover and 10 bolt on the ring gear .
It get 40 teeth with number 2-GM-1235126-13-40-4-85 stamp on it .
The center cage get B-5 04*8 and C48FC stamp on it .

What to loock for to know habout G-80 model .:eek::

many year ago i was told it is limited slip by a shop who rebuil one of my previus differential, maybe i was missleaded at that time, who know?
The picture is the best of my knowledge. what to look for the locking differential mecanism to konw the difference with limited slip mecanisme?:help:
 

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Discussion Starter #5
still work

Hi TFLundyB275 ,

yes still work.
The original owner was an electricien an alway carry few tools around(he was the boss father,technical or moral support )
I drive it on the old body 200 miles and it sound fine .Very low rpm at 65mph.No wearing sign visible one the gears ,oil is clean no metalic residue on the magnet.


Somting else to look before the swap ?:help2:
 

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Tigman,
You are measuring in the wrong direction. To determine size, for those of you that can't tell by just looking as I can, you need to measure the diameter of the ring gear. You have an 8.5 inch 10 bolt rear axle with a locking differential. These can also be called a limited slip, but they are actually a locking diff. For inspection, just carefully inspect the governor flyweight gear,(visible on outside of case) it has small teeth that resemble a starter bendix gear, it meshes with a wave gear that has a lot of teeth on the outside of it. Inspect to make sure that there are no teeth missing. This unit does have clutches in it to help it lock up, so special gear oil or limited slip additive is required or in my case, I preffer synthetic gl5 gear oil without additive. If you are planning on swapping this rear axle into a different truck, be aware that the rear axle in vans is about 3 inches wider than the same axle in a pickup:eek: The carrier on a 10 bolt with 3.08 gears is interchangable with most of the lower gears however should you decide you want more power, you could go to 3.73 or 4.10 and keep the locker.
 

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Discussion Starter #7
3.08 swap

You have an 8.5 inch 10 bolt rear axle with a locking differential.

For inspection, just carefully inspect the governor flyweight gear,(visible on outside of case) it has small teeth that resemble a starter bendix gear, it meshes with a wave gear that has a lot of teeth If you are planning on swapping this rear axle into a different truck, be aware that the rear axle in vans is about 3 inches wider than the same axle in a pickup:eek:

The carrier on a 10 bolt with 3.08 gears is interchangable with most of the lower gears however should you decide you want more power, you could go to 3.73 or 4.10 and keep the locker.
Hi D.Camilleri,

thank's for the quick response, After mesuring in the right direction it's 8.5 inch 10 bolt ok.

So it is a eaton gov loc,good or bad???

After good inspection the wave gear and the governor are like new and everyting look good into the cage.:)

Your right my pick-up is not the right size so i think i have to interchange the gear set.

1rst time for everiting,:think: and the locker is the BONUS.It look to be a bolt-on job if i dont move the shims.

Actualy i have 4.10 ratio and i never need much power to carry my atv.
Most of my driving is on highway :driver:,so i look to reduce my mpg.
:D
 

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gov locs are good if they are used the way the factory meant, that doesn't mean drag racing or extreme off roading. It will interchange, but gear set up is a bit more involved than what you think and needs to be done right or the gears will be ruined.
 

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wats the difference if there is one between a gov-lock and a locker
 

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Think limited slip with the Gov-Lock (G80). The G-80 units will lock up but generally quit after a few years of use off road. A true locker wont wear out and locks the axle shafts together when under power and you have any wheel spin. The Gov- lock needs a couple of tire rotations to get the centrifical force built up to apply pressure to the clutch pack to grab the axle shafts (short version) it will stay "locked up" as long as the power is there or you use the brake to hold the lock up. The gov-lock pushed hard off road will puke its guts or burn the clutch paks out and it will not work anymore. As a general rule if its bad we dont fix them for off road trucks. If you want to keep the 10 bolt get rid of the gov-lock and get a "lunch box " locker. IE:powertrax
The 10 bolt is a really good axle as long as you know its limits, and for street use I would not reccomend a locker above the Gov-lock.
 

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Discussion Starter #11
What you have there is a G-80 10 bolt locking differential. Or as some of us call them eaton gov loc;)


Hi ,D.Camilleri sorry for my translation mistake:eek:: , i mix up inquire and information .

My aplication is highway 80% i live 55miles from work and i travel it for the past 15 years and i plan to do it many years to come, 15% downtown and 5% GOING TO THE ATV PIT TO HAVE FUN WITH MY POLARIS EXPRESS 400 .

Any recommandation do it right the first time for the gear set up procedure :help2:

or i better make a post in the drivtrain section
 

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Good info,:) and to anyone who made the same mistake as I did when I first read this. It's NOT bad spelling:eek: It's English with a FRENCH accent:cool2:
 

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Do a search in the drivetrain section for info on setting up R&P or contact Randy's Ring and Pinion, they have some good set up info. Setting up a R&P takes a special feel and isn't something for most backyard mechanics. I have done lot's of them and most mechanics I know don't know how to do them right. Requires some special tools also. Best bet is find someone local and have them do the swap for you. If you bring them the axles out of the vehicle with axle shafts removed it can save some money.
 

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Eagle Eyes
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So yeah...I still thought GM didnt put any locking differentials in 10 bolt axles.
 
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