Locking/Lim. Slip Diff. on 03 Sierra

86'er · Dec 12, 2005

I'm wondering if 2-wheel-drive Sierras back in 2003 had an option for a locking differential or if 2WD's only got the limited slip.

I asked a dealer about this and he seems to think that the G80 locker wasn't an option on the 2WD but was often standard on 4 X 4's.

I'm having some confusion on this matter because on later models a G80 locker was a package option on some 2WD's (i.e. the Nevada Edition Sierra).

Would anyone be able to shed some light on this?

Steve Perry

John DiMartino · Dec 12, 2005

As far as I know it was available on all models, it was only standard on a few select models like the ZR2 S10,and Blazer. Just look in the glovebox at the build sheet for the G80 code.I personally dont like the G80 on 1500s unless they have the 9.5" ring gear.The 10 bolt 8.5" carrier assy is weak,and they are known to break in 1/2 when used hard if they have the G80 locker.

Z71 · Dec 12, 2005

from GM info dealing with rear axle additives but provides info on the G80 option..

The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

I have had several 1500 GM trucks with G80 and mnay 4x4 1500's with G80 and never once had a problem with any of them. If they break, its from abuse and nothing else IMO. Like one person I know off who got stuck and was too lazy to get out and shovel so he kept spinning the tires till one dug thru the mat and hit pavement and snapped of an axle. DId not damage the G80.

86'er · Dec 13, 2005

Thanks John, and Z71 for your responses.

I guess I ask specifically because I wasn't aware that GM used anything except the G80 locker and was a tad surprised when this dealer told me this truck I'm interested in buying had a limited-slip diff.

Essentially it'll be the determining factor as to whether I buy it or not, as I live in Saskatchewan and a locking diff on a 2WD is the minimum one usually needs to get through the ice and snow with any degree of comfort.

Steve Perry

86'er · Dec 13, 2005

86'er said:
Thanks John, and Z71 for your responses.

I guess I ask specifically because I wasn't aware that GM used anything except the G80 locker and was a tad surprised when this dealer told me this truck I'm interested in buying had a limited-slip diff.

Essentially it'll be the determining factor as to whether I buy it or not, as I live in Saskatchewan and a locking diff on a 2WD is the minimum one usually needs to get through the ice and snow with any degree of comfort.

I suppose I need to frame that in the form of a question.

Did GM use limited-slip differentials in their 2WD trucks (around the 2003 MY)or did they only use the locker?

John DiMartino · Dec 13, 2005

I cannto answer that with 100% certainty,but Gm has always put lockers in trucks,and limited slips in cars.I have worked on a lot of Gm trucks,and I havent seen any trucks built since the mid 80s with a a LSD,Ive only seen the lockers.I would think the answer would be no,but I am not 100% sure.If it is that important to you,take a floor jack,and jack the rear in the air or at least one tire,and spin them,if they spin freely opposite each other,and theres no G80 on the build sheet,then its an open diff.If it wont spin and the brakes arent on its got to have a LSD.a g80 will spin like an open diff until a certain speed/load differential,then it engages solid.

ratlover · Dec 13, 2005

Pretty positive that if it was a truck it got a locker not a limited slip.

I know of guys that have blown 10 bolt gov locks apart with normal sized tires and never towing or wheeling thier stuff. Govlock in the smaller axels is weak IMO. Abuse(especially doughnuts) and burnouts and tromping on the gas when going around corners is really hard on these things(even the ones they put in the HD's) and I would avoid it.

Radguy · Dec 14, 2005

I have a "locker" in my truck, but it's not a true locker. I can get 1 tire to spin on wet or snowy roads. On a dry road I have a hard time breaking the tires loose. It's more like a limited slip. I true locker locks the axles so one will not spin without the other. JMO but a detroit would be alot better, but then you would have to be more careful as the rear end would have more of a tendency to kick out sideways.

derekbroerse · Dec 14, 2005

Personally, I would really prefer a nice tight limited slip unit to a locker--hate the Lock-Rite in my truck and Detroit in my friend's... make the trucks feel like junk.

Seen the 10-bolt Gov-Loc blown up a few times--the 7.5" and 8.5" versions, both in trucks... mind you I would call both 'abuse'. Trucks in the 70's with the 12 bolt still had clutch-type posi units. We have one here that we used for parts for a Chevelle 12 bolt. Not sure if the 8.5" 10 bolt ever got a clutch type posi in a truck or not. Full sized Caprices did for sure. Got a bunch of those.

The Gov-Loc in my brother's S15 Jimmy works flawlessly.

I have a Dana 70HD in one of my dually parts trucks with something--not sure if that would be a posi or a locker--anyone know?

wyldman · Dec 14, 2005

The Dana 70 probably has a regular clutch type limited slip.

EZSnow · Dec 14, 2005

They don't call them gov-bombs for nothing!!

I had a gov-loc in the 14-bolt in my '99 2500. With a little wheel speed and a few bumps on the brakes, it would lock up with one wheel in the air. I liked it. Mine never blew up, but man do they groan when you're three-wheeling!!

Z71 · Dec 14, 2005

You guys must be hard on them as I have not had one fail. Here is a list of all prior and existing vehicles that I had/have G80 in them;

1962 Pontiac Gran Prix (used, rest were new)
1966 Impala SS396
1970 Chevelle SS454
1972 El Camino SS350
1973 Chevelle SS350
1975 K5 Blazer
1977 Monto Carlo
1979 G20 Custom Van
1982 S10 Pickup
1984 Olds Delta 88
1987 Chev Silverado 4x2
1988 Chev Silverado 4x2
1989 Chev Silverado 4x4
1992 Chev Silverado 4x4
1995 S Blazer 4x4
1996 Silverado 4x4
1999 GMC Sierra 4x4
2001 GMC Sierra 4x4
2002 Trans AM WS6 LS1
2002 GMC Sierra 4x4*
2005 Cadillac CTS 3.6L LS*

*current rides

I won't buy a vehicle w/o G80 or if I find one I want, they dealer has to install it or I walk. Up here (Lake Superior region) G80 are always easily found in dealer lots.

John DiMartino · Dec 14, 2005

Z71,you dont have to be hard on the to make them explode.It is so easy to blow the ones in the 1/2 tons and the S trucks into next week.A little patch of ice under one tire when taking off,will unload the tire on ice,if you dont get your foot off the throttle,the trans will quickly shift to second,the locker will try to kick in and the gov lock will literally break the carrier in 1/2.I have seen so many that i wouldnt buy a 1/2 ton or less with a G80.The 3/4 ton or 1/2 ton w 14 bolts are MUCH stronger,although they can fail if pushed too,it just isnt that likely.I have an s10 sitting here now with the carrie broken in 1/2,ive had 3 1500s break them in my area that are friends of mine.

derekbroerse · Dec 15, 2005

Z71 said:
You guys must be hard on them as I have not had one fail. Here is a list of all prior and existing vehicles that I had/have G80 in them;

1962 Pontiac Gran Prix (used, rest were new)
1966 Impala SS396
1970 Chevelle SS454
1972 El Camino SS350
1973 Chevelle SS350
1975 K5 Blazer
1977 Monto Carlo
1979 G20 Custom Van
1982 S10 Pickup
1984 Olds Delta 88
1987 Chev Silverado 4x2
1988 Chev Silverado 4x2
1989 Chev Silverado 4x4
1992 Chev Silverado 4x4
1995 S Blazer 4x4
1996 Silverado 4x4
1999 GMC Sierra 4x4
2001 GMC Sierra 4x4
2002 Trans AM WS6 LS1
2002 GMC Sierra 4x4*
2005 Cadillac CTS 3.6L LS*

*current rides

I won't buy a vehicle w/o G80 or if I find one I want, they dealer has to install it or I walk. Up here (Lake Superior region) G80 are always easily found in dealer lots.

I would also say that the majority of your list use clutch-type positraction units, not a "Fling-locker". Definately everything from the '84 Olds and back. Not sure if they use the code G80, its only an option code.

Locking/Lim. Slip Diff. on 03 Sierra

86'er

John DiMartino

Z71

86'er

86'er

John DiMartino

ratlover

Radguy

derekbroerse

wyldman

EZSnow

Z71

John DiMartino

derekbroerse

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