Gear ratio question

[nad]

I'm suspicious that my Jimmy has some crazy high gears in it, like 2.73's or something. The problem is, the sticker on the door jamb is faded to nothing, and I just changed my diff fluid, so I don't want to take the cover off and look.

Any other way to tell what gears are in it? My buddy said I could call the dealership and give them the VIN and they would tell me, but is there an easier way? An online website that would tell me if I type in my VIN?

Thanks for the help guys.

 

[nad]

Actually now that I think about it, the guy I bought it from had some rear end shop magnets all over the dash, so it's possible that it was re-geared since it's left the factory. But I'm sure the front diff is probably still geared with factory gears.

 

[Russell]

Your VIN won't tell you the gear ratio... One way to find out without taking the diff cover off is to jack up the rear end, turn a tire a full rotation, and watch how many times the driveshaft turns.

It isn't really accurate (3.42s and 3.73s look very similar) but you can get a good ball park idea of your gearing.

 

[Slapperbar]

Look in the glove box for the RPO codes.

 

[nad]

And what do those codes tell me? I've seen them, but they don't really give me any clues.

 

[Russell]

One will tell the factory gear ratio

 

[Slapperbar]

It should be a G sumthin sumthin, i.e. GT4= 3.73, GT5= 4.10, GS1= 2.73, G96= 3.55, etc adnausium.

 

[Slapperbar]

I have the book open in front of me right now.

 

[Slapperbar]

If you can't tell, PM me the list and I'll look it up for ya.

 

[nad]

Okay, I just went out and looked, and the only label that has any numbers on it is the "Service Parts Identification" label. The only sequences that started with "G" were G03 and G80.

What am I missing?

 

[habitatxskate]

this is what i dug up
G80 -- AXLE REAR, LIMITED SLIP (POSITRACTION)

 

[nad]

Still doesn't tell me my ratio.

 

[Slapperbar]

G80 is the infamus gov bomb diff, I'm still looking for G03 or GO3 it's not on my list.

 

[Slapperbar]

What are the rest of the codes on that label?

 

[dyeager535]

Double check that GO3.

I don't see that referenced in any site I checked, and GM was pretty good about using RPO's for quite some time. I can find a GH3, GM3, GM8, and GT8, but that's it.

It very well could be a valid RPO, but you'd need an '82 service manual to figure that out if it was short lived.

 

[nad]

It's actually G06, sorry. I can't find G80 anywhere. I'm pretty sure I don't have a gov-loc. It's just an open 10 bolt from what I can see.

 

[Slapperbar]

I have no GO and only as low as G11.

 

[Slapperbar]

GU6 is 3.42

 

[Slapperbar]

in post 10 you said you had G80 for the diff.

 

[nad]

The only 2 codes I have that could be a rear diff were G06 and G80. I can't find either.