Carrier question?

[Uno99]

I have either 2.56 or 2.73 gears in in rear according t the RPO codes and I am getting ready to order my new ring and pinion. On Summit they offer a 3.73 gear for a 3 series carrier. Is this the "THICK" Gear that is made for the 3 series carrier. Has anyone used this setup?  I always thought you had to swap carriers?

[VileZambonie]

You should verify what you actually have before you make your order.

Don't forget shim assortment and bearings.

[HAULIN IT]

Uno, Is this for the (8.5"?) in your '81 or something else? The 8.5" has a large spread of case usage, 2.73 is the same as 3.73, & is what they call the three series) The gear your referring to (without throughly checking) sounds like the normal thing to use, the THICK wording should only apply if you are trying to put it on a two series carrier. If your working on a 12 bolt things are different. As mentioned, you need to check the changeability once you know for sure what you have in yours. Lorne

[Stewart G Griffin]

Actually, what you could do is go down to the local chevy (or gmc) dealer and give them the vin# and they should be able to look up what you have or at least be able to tell you what GQ-1 code gear was for 81.  The dealer is a really good source for info (see my other post "AXLE CODES")

Being that it's an 81, i would be willing to bet it's 2.56;  i also have GQ-1 "rear axle standard" on my 83 and in 83 it was a 2.56.

Did you try jacking up one wheel, spinning it 2 times and counting driveshaft rotation?  Or taking the cover off.

Are you going to be doing the gear install by yourself?

[Uno99]

The Dealership told me I have either 2.56 or 2.73 and a Corp 8.875 12 bolt rear w/ locking diff

[HAULIN IT]

Uno, Ok, A 12 bolt 2.73 would be a two series carrier & the 3.73 is a three. You would need a "thick" 3.73 ring gear (I'm not sure if one is available) to put it on the two series carrier you have.  If you get a hold of a three series carrier, you would use a regular three series ring gear. This sounds like the one your describing from Summit. Hope this helps, Lorne   

[Uno99]

OK Thx HAULIN IT......So the highest Gear I can use with my current carrier is 3.42 right?

[Captkaos]

Yes.