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GMC Forum: Possi Or Limited Slip
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  #1  
Old 11-06-2011, 05:39 PM
95SL4x4 95SL4x4 is offline
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Default Possi Or Limited Slip

I recently bought a used 95 GMC Sierra 4x4 with 245,000 km/s on it. Overall the truck is in great shape and runs exceptional. Only thing that needed fixing was the exhaust, inner driver side door handle, and some brake lines. Will be a joy to ride this beast no doubt whenever i get it back from it's physical.

Needless to say i have a lingering question regarding the rear differential. I've been looking online since i bought the truck and have been trying to determine if i have a limited slip differential or a possi, also better known as a locker. I've read lot's about G80 being the GM code for a locking rear diff. Am i right in assuming this correctly..? Also, i looked in various places in the truck like the glove box and on the inside part of the driver side door for this code but cannot find it anywhere. Any help would be greatly appreciated. I looked for numerous hours on end online with no end result.
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Old 11-06-2011, 06:26 PM
Z15 Z15 is offline
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Limited slip is not the same as a locker. Posi is just another name for limited slip. Typically trucks with G80 use a locking rear differential. Inside the glove box should be a service parts label and on that label is a list of all option codes on the truck. They are list alphabetically and the code for the locker is G80. If its not on the list its not on the truck. G80 were not common back in the 90's. You had to order it as it NEVER came as standard equipment with any package, always extra cost option the customer has to chose and rare even for vehicles in snow country. Even truck I had had a G80 and the only way I could get it was to order the truck, dealers rarely stocked trucks with it.

GM use the same G80 for both limited slip (posi) and locking differential. What is in the rear is dependent on the make and model. Cars typically use the limited slip (posi).

G80 Differential, heavy-duty locking rear
G80 Differential, automatic locking rear
G80 Differential, heavy-duty automatic locking rear
G80 Differential, limited slip rear
G80 Differential, limited slip
G80 Differential, locking, heavy-duty, rear
G80 Differential, Zexel-torsen, limited-slip, rear
G80 Differential, automatic
G80 Rear Axle: Positraction
G80 Locking, Rear Axle
G80 Axle Positraction Limited Slip
G80 Differential, locking, rear
G80 AXLE POSITRACTION LIMITED SLIP

Learn about the difference with these vids

http://www.youtube.com/watch?v=k5DPoXWxDfk&NR=1

http://www.youtube.com/watch?v=AjymmXvBYsI

http://www.youtube.com/watch?v=p8nAbg5suFw

Last edited by Z15; 11-06-2011 at 06:33 PM.
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Old 11-06-2011, 07:04 PM
95SL4x4 95SL4x4 is offline
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Thanks for the quick reply and for the videos. As you stated i have that parts label in the glove box but did not come across the G80 code like you stated. Though you also stated that trucks in the 90's did not have this feature and was something you had to specially order.

So what does this mean for trucks that were built in the 90's..? And is there any way to determine what kind of rear end i have in my 95 GMC Sierra 4x4..? Thanks again for the help, much appreciated.
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Old 11-07-2011, 07:47 AM
Z15 Z15 is offline
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Yes

Only 2 types of rear axle were available; the standard open axle or the G80 optional extra cost Eaton locker.

If the locker were ordered G80 would be on that label.

All the rear axle options are coded on that label and start with G?? and use this list to compare. Right now about all you can find out is the ratio.

Here are all the G codes in existence, just because a code is on this list do not assume it would apply to your truck. This is across the complete GM fleet.

G50 Springs, heavy-duty rear
G55 Springs, light-duty rear
G63 Side rails, roof-mounted
G63 Luggage rack, delete
G63 Luggage rack, roof-mounted, Black
G63 Provisions Luggage Carrier, Roof
G64 Automatic Level Control, self-adjusting
G65 Level Control Manual, Self-Adjusting
G67 Suspension Package, rear load-leveling
G67 Suspension, rear, load-leveling
G67 Automatic level control
G67 Suspension, rear load-leveling
G69 Automatic level control
G69 Level Control Auto, Air, HD
G75 GVWR, 4550 lbs. (2064 kg)
G80 Differential, heavy-duty locking rear
G80 Differential, automatic locking rear
G80 Differential, heavy-duty automatic locking rear
G80 Differential, limited slip rear
G80 Differential, limited slip
G80 Differential, locking, heavy-duty, rear
G80 Differential, Zexel-torsen, limited-slip, rear
G80 Differential, automatic
G80 Rear Axle: Positraction
G80 Locking, Rear Axle
G80 Axle Positraction Limited Slip
G80 Differential, locking, rear
G85 Differential, limited slip
G86 Differential, limited slip
G86 Differential, limited slip, heavy-duty, rear
G94 Differential, full-locking rear

GAM Sales code, federal government
GAM Vehicle Government
GAT All-Terrain Package
GDY GVWR, 4538 lbs. (2058 kg)
GEA GVWR, 4718 lbs. (2140 kg)
GEC GVWR, 9800 lbs. (4445 kg)
GED GVWR, 9700 lbs. (4400 kg)
GGC Grille, Black painted
GGC Regular production accessory, Grille inserts, custom
GH0 3.54:1 Rear Axle Ratio
GK9 Rear Axle: 4.63 Ratio
GM8 Rear axle, 2.56 ratio

GMC Pontiac East Assembly
GMC Plant Code Pontiac, MI, USA
GND Ground Effects Package
GT4 Rear axle, 3.73 ratio
GT4 Rear Axle Ratio, 3.73
GT4 Rear Axle: 3.73 Ratio
GT4 3.73:1 Rear Axle Ratio
GT4 Axle Rear 3.73 Ratio (DUP With 5 x 1)
GT4 Axle ratio, 3.73
GT5 Rear axle, 4.10 ratio
GT5 Rear Axle: 4.10 Ratio
GT5 4.10:1 Rear Axle Ratio
GT5 Axle Rear 4.10 Ratio (DUP With GT8)

GTF G5 Appearance Package
GTY Rear axle, wide-track
GTY Axle Wide Track
GTY Wide Track Rear Axle
GU2 Rear axle, 2.73 ratio
GU4 Rear axle, 3.08 ratio
GU4 Rear Axle: 3.08 Ratio
GU4 3.08:1 Rear Axle Ratio
GU4 Axle Rear 3.08 Ratio
GU5 Rear axle, 3.23 ratio
GU5 Axle ratio, 3.23
GU6 Rear axle, 3.42 ratio
GU6 Rear Axle: 3.42 Ratio
GU6 3.42:1 Rear Axle Ratio
GU6 Axle Rear 3.42 Ratio
GU6 Axle, 3.42 ratio
GW1 Rear axle, 3.91 ratio
GW1 Axle ratio, 3.91
GW5 Axle, 3.16 ratio

GZV GVWR , 6411 lbs. (2908 kg)
GZW GVWR , 6459 lbs. (2930 kg)
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  #5  
Old 11-07-2011, 10:10 AM
Molson02536 Molson02536 is offline
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Quote:
Originally Posted by 95SL4x4 View Post
I recently bought a used 95 GMC Sierra 4x4 with 245,000 km/s on it. Overall the truck is in great shape and runs exceptional. Only thing that needed fixing was the exhaust, inner driver side door handle, and some brake lines. Will be a joy to ride this beast no doubt whenever i get it back from it's physical.

Needless to say i have a lingering question regarding the rear differential. I've been looking online since i bought the truck and have been trying to determine if i have a limited slip differential or a possi, also better known as a locker. I've read lot's about G80 being the GM code for a locking rear diff. Am i right in assuming this correctly..? Also, i looked in various places in the truck like the glove box and on the inside part of the driver side door for this code but cannot find it anywhere. Any help would be greatly appreciated. I looked for numerous hours on end online with no end result.
Easiest way for you to get the PRO codes and options that was ordered is to go visit your local GM dealer parts department and ask them if they can print out your Sierra PRO code options.

All they need is your Vin number and they can print out the order options your Sierra came with and when gear ratio to your Sierra will be on the print out. Hope this helps and makes life easier and not, this service free with a smile lol.

Molson02536
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  #6  
Old 11-07-2011, 10:22 AM
95SL4x4 95SL4x4 is offline
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Thanks for the help guys, much appreciated. Will check further into it and keep ya posted.
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Old 11-07-2011, 04:51 PM
Z15 Z15 is offline
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I don't think you will have any luck finding RPO info at the dealer. Last time I checked they told me that can go back only about 10 yrs (if that) before the data is purged from the system. Worth a try I guess. Once a vehicle is out of all warranties GM has no interest in keeping data on it.


You can buy a dealer invoice from here http://www.gmmediaarchive.com/

Vehicle Invoices ($50)
The vehicle invoice collection is the documentation of the vehicle cost broken out by model and factory options. It contains the original ship to dealer information, MSRP and invoice number that General Motors used to bill the dealer. The collection is archived on microfilm, microfiche, CD and is organized by VIN number. The collection covers almost all cars & trucks produced in the United States starting in the mid 1970's.* Vehicle Invoices are printed from microfilm or microfiche then scanned and emailed as an Adobe PDF for $50 USD.

Most requests for copies of dealer vehicle invoices are reproduced from microfilm and microfiche. Copies of these records may vary in quality, depending on the condition of the archived record. We will give you the highest reproduction quality possible from these media sources. We will notify you if the invoices are not legible or unavailable.
Vehicle invoices are available for the following years: *

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Cadillac from 1980
Chevrolet from 1977
GMC from 1976
Oldsmobile from 1977
Pontiac from 1987
Saturn from 1994

* Excludes Fleet and Exported vehicles
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