G80 9.5 rear end

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

96z71sas

OBS Enthusiast
Joined
Jan 23, 2018
Messages
94
Reaction score
32
Location
Pittsburgh
Does anybody know how to identify the rear end without taking diff off? It’s 14 bolt semi floater 8 lug on a 96 k2500 not posi I want posi I think it’s a 9.5 g80? Any help would be great thanks
 

Nad_Yvalhosert

I'm Awesome
Joined
Oct 11, 2016
Messages
1,666
Reaction score
2,085
Location
Rochester, NY
8 lug semi float is gonna be a 10.5"
6 lug semi float is the 9.5"

GM doesnt use posi-traction in their trucks. They come with a mechanical locker that acts like an open diff when the wheel speed differential (difference between left tire and right tire) exceeds 200 RPMs. G80 is the code.
As asked above, what are your RPO codes? It will tell you when you decide it. The axle code will start with a G. Like GU6 or GT4...

For instance, my '98 Suburban 2500 has 4:10 & an open diff. Likely yours is too.
 

someotherguy

I'm Awesome
Joined
Sep 28, 2013
Messages
9,784
Reaction score
14,138
Location
Houston TX
G80 code on the SPID label (option code label in the glovebox) for the Eaton Gov-Loc locker option on these trucks. It ain't posi.. it's a locker. This of course only applies if the rear end hasn't been swapped out. So on to my next points:

Go ahead and pull the cover. You want to know what condition it's in before you buy it, right? Check condition of the teeth, look in the housing for any broken parts, condition of the lube, crap stuck to the magnet, etc.

With the cover off, you can easily identify the Gov-Loc by its crazy appearance of the carrier. You can also confirm the gear ratio at that point by looking for the numbers stamped into the edge of the ring gear. Divide the larger number by the smaller number. 41 by 11 for example would be 3.73's

Richard
 

stutaeng

I'm Awesome
Joined
Aug 7, 2019
Messages
3,410
Reaction score
4,348
Location
Dallas, TX
14 bolt got it's name because....get this...the differential cover has 14 bolts! LOL.

On the C/K 2500 series truck and Suburbans, the SBC option got a 9.5 Semifloat, while the BBC/Diesel options got the Full-float 10.5". This is true of all the civilian vehicles I've come across. The only exception will be government-spec vehicles. Those may be different.

On the G80, if the truck drives get one wheel on wet pavement and hit the gas. RPO code if it is available, but otherwise there is not "marking" on the outside that would tell you if you have the G80.
 
Last edited:

red98

I'm Awesome
Joined
Feb 3, 2020
Messages
369
Reaction score
714
Location
Washington
Does anybody know how to identify the rear end without taking diff off? It’s 14 bolt semi floater 8 lug on a 96 k2500 not posi I want posi I think it’s a 9.5 g80? Any help would be great thanks
There's 5 rear ends IIRC

The "10-bolt/14-bolt" refers to how many bolts you can count on the diff cover.

8.5" 10 bolt
9.5" 14 bolt 6-lug SF (rare-ish)
9.5" 14 bolt 8-lug SF - yours
10.5" 14 bolt 8-lug FF
10.5" 14 bolt 8-lug FF Dually (idk exactly how this one is different from the other FF 14-bolt but I imagine it is)

Then the other questions are:
What's the ratio: I've seen 3.42s all the way thru 4.10s from the factory. There's some math you can do by counting the teeth or something to figure this out, or RPO codes.
Locker or Open: Either has the g80 RPO code in glove box, or its open.

*All of this assuming its a stock rear*
 

Supercharged111

Truly Awesome
Joined
Aug 20, 2015
Messages
12,612
Reaction score
15,233
There's 5 rear ends IIRC

The "10-bolt/14-bolt" refers to how many bolts you can count on the diff cover.

8.5" 10 bolt
9.5" 14 bolt 6-lug SF (rare-ish)
9.5" 14 bolt 8-lug SF - yours
10.5" 14 bolt 8-lug FF
10.5" 14 bolt 8-lug FF Dually (idk exactly how this one is different from the other FF 14-bolt but I imagine it is)

Then the other questions are:
What's the ratio: I've seen 3.42s all the way thru 4.10s from the factory. There's some math you can do by counting the teeth or something to figure this out, or RPO codes.
Locker or Open: Either has the g80 RPO code in glove box, or its open.

*All of this assuming its a stock rear*

Dually floater is a different width, that's the only difference I'm aware of. Then of course some had slip on drums and some did not.

There's an 11.5 ring gear full-float axle in there somewhere.

Might be on the C3500HD.

It would have to be the legit HD , because even the 12k (presumed) GVW C&C I saw in the boneyard had the 10.5".
 

stutaeng

I'm Awesome
Joined
Aug 7, 2019
Messages
3,410
Reaction score
4,348
Location
Dallas, TX
The 14 bolt 11.5" full float only came in the GMT 800/900 trucks with the 8.1 big block and 6.6 TD. I believe all the 2KXX 2500/3500 series are now running the 14 bolt 11.5" axle. I'm sure it's same or nearly the same axle as the Ram 2500/3500 with the 11.5" ring gear.

The GMT 400 3500 HD (GVWR = 15,000 lbs) ran Dana 80 and some Rockwell axle. REALLY heavy stuff. Looks almost like what the semi trucks run.
 
Top