Im looking at a few cars to get the rear end out of. Im under the impression that most v6 cars have 3.42s? If I want a 3.42 or 3.23 rear end what should I look for as far as donor cars?

 

Look at the RPO codes on the production stickers. They are located either under the center console lid, or under the lid on the lockbox in the trunk. The codes you are looking for are:

GU5 - 3.23
GU6 - 3.42
G80 - Posi

V6 cars with the manual transmission(T5) should have the 3.42's in them. That's what my 92 came with. 3.23's should be cars with the 305 and T5. Are you just looking for the gears, or the whole rear axle?

 

Many of the cars Im looking at do not have the rpo codes. Ill try to find them to make sure. Do the auto v6s also have the 3.42s? According to the links at the bottom of the page the 3.42s were standard on any v6 from like 85. Just gettin some info.

 

How close are you to PA? I just pulled the rear out of my 92 to swap in a 4thgen rear. Its got the 3.42's in it with drum brakes. I also have a set of 3.23 gears from the 4thgen rear.

You can also figure out what gears a vehicle has by either pulling the cover off the diff and checking the ring gear or if the rear is in the air, spin a rear wheel while counting the number of revolutions the driveshaft makes. A 3.42 gearset will turn the driveshaft about 2 1/2 times for every 1 turn of the rear wheel, and a 3.23 gearset will turn it about 2 1/4 times.

The reason I asked if you were looking for the whole axle, or just the gears is that you can pull the gears from any 80's or 90's GM 10 bolt, except for the fullsize trucks. For example, the 4thgen rear I just swapped into my Camaro had 3.23 gears in it when I pulled it from the junkyard. I took those out and put in a set of 3.73's I pulled from an 89 S10 at another junkyard.

You can check the 10-bolt FAQ for the list of gears used with various engines. I'm pretty sure its fairly complete and accurate.

 

Im a good bit aways from PA, im in southern TN. Thanks though. Im wanting a whole rear end. From the bottom of this page I came up with this. 1985-1989 all v6s had 3.42s with the 4cyl having 3.73s. Before and after that the manuals had 3.42s with the autos having 3.23s. This is for camaros, im assuming its the same for firebirds?

 

Where in PA are you? Do you still have the 3rd gen 3.42 rear end? I am in northern NJ and may be interested in it.

 

Yeah, I still have it. I'm in Johnstown. Its on the other side of the state from you. About 4 hours from Philly, and 1 1/2 hours shy of Pittsburgh.

 

It should be the same for both, yes. There was also the 9-bolt rear ends, but they are rare to find. There are also some with 3.08 gears as well. Those were mostly the 350 TPI cars I believe.

 

I have the stock 3.23 disc brake rearend I just took out of my 91 GTA to swap to a 9" I have the calipers and brake lines but the rest of it is there. You can have it if you get it out of my way.

 

i also have a lsd 10 bolt with only 30,000 on it. internals are very clean it is a disc brake read end out of a 85 iroc z t5 manual. pm for info located in il.

 

It is easier to spin & wheel & watch driveshaft rotations to get the R&P size, than it is to pull a diff cover & count teeth.

 

No need to count teeth. The gear ratio is stamped on the ring gear. Just turn the axle till you can find the stamping and divide the numbers.