get any and all numbers or codes from it and measure width and also distance from the flange the ring gear bolts to on the diff unit over to the closest side end of the unit where the diff unit bearing is, out to the very end/edge

this will tell us what series unit it is, 2, 3, or 4 series

with 3.73 it should be a 4 series but it may be 3 and have a thicker ring gear 3.73 set that is aftermarket bought because no thick 3.73 ring gear sets for 3 series were made from factory

or get good pics of both ends of it and width measurement and diameter of the widest point of it where the ring gear mounting flange sits

also how many bolts hold the ring gear on

then me or someone else can ID it

does it have springs and clutch disc pack type posi?

or is it a gov-ock unit with a funky spring unit thing on it ?

if its a gov lok then run away fast it is garbage and these are known as the grenade-lok units due to their reliability of only blowing up, and no holding up to anything except maybe a 90hp 4 cylinder if youre lucky.

 

I havent seen it yet, but he tells me it may be from something like a 2.50 or 2.73 gear. He wants to put it in his 3rd gen which has a 3.73 open diff. I'll get a good look at it tonight and some pics to post.

Edit: Pics

 

added pics above. Does this help anyone I.D. the type?

 

no 3rd gen camaros came with 3.73's i belive the highest was 3.23 but you may have been able to get one with a 3.42, but all of these would have been the 3 series carrier's, the carrier pics you posted look alot like the G-80 unit i have sitting out in my garage, i have only heard bad things about so that is why it's not in my camaro, i dont belive that GM made a 4 series carrier for the 3rd gen (95%sure), i cant tell you wether the carrier you have is a 2, or 3 series i know the 3 series were rare in these cars, most Z28's and IROC's had either the 2.73's or the 3.08's witch both are in the 2 series, you can buy 3.73's and even 4.10's to go into a 2 series carrier but they are just "thick gears", my guess would be this is what you have and the 3.73 and 4.10's for the 3 series carriers are normal size, i know i haven't helped you much, but could you still find out what the carrier came out of, oh come to think of it all the 3 series carriers are "posi" in the 3rd gens, so i would deffinatley say what is in the rear right now is a 2 series

 

Well, SOME third gens had 3.73s because he has one. Original rear, no mods, open rear 84 Z28. Stamped into the ring says 3.73. Even counted the teeth and did the math. This car is an original 3.73.
The pics I posted is what he wants to put in because it's a posi unit. He's just not sure if he needs the spacer or not because he doesnt know what series that one is. We don't know what it came out of.

 

If you have the original rear opened like you said, it is an easy comparison. The difference is in the "height" of the ring gear flange in relation to the centerline of the carrier. There is slightly more than an 1/8" difference (.140" IIRC). You can lay or hold them side by side, or stand them up on a bench, the difference will be readily apparent. For the 7.5"(8.5" also) there are only 2 series and 3 series carriers, no 4 series. 4 series gears for these rears fit on the 3 series carrier.

So, you only have two choices, it will match or it won't. If the posi you have is a two series, it will hold the ring gear too far away from the pinion for it to mesh correctly, and thusly need a spacer. I wouldn't be afraid of a spacer in your case, you will break something else in the rear end before the spacer will cause a problem.

Unless someone can come up with measurements from say the end of the bearing snout to the gear flange, or a list of casting #'s, either of which is what I think you are looking to find, that's the best I can do. Have you tried any of the third generation forums? They may be more help.

What you have pictured seems to be a 2 series to my eye, ring flange is real close to side bearing, and looks to be an Auburn unit. BUT DON'T take my word for the series

 

If you have the original rear opened like you said, it is an easy comparison. The difference is in the "height" of the ring gear flange in relation to the centerline of the carrier. There is slightly more than an 1/8" difference (.140" IIRC). You can lay or hold them side by side, or stand them up on a bench, the difference will be readily apparent. For the 7.5"(8.5" also) there are only 2 series and 3 series carriers, no 4 series. 4 series gears for these rears fit on the 3 series carrier.

So, you only have two choices, it will match or it won't. If the posi you have is a two series, it will hold the ring gear too far away from the pinion for it to mesh correctly, and thusly need a spacer. I wouldn't be afraid of a spacer in your case, you will break something else in the rear end before the spacer will cause a problem.

Unless someone can come up with measurements from say the end of the bearing snout to the gear flange, or a list of casting #'s, either of which is what I think you are looking to find, that's the best I can do. Have you tried any of the third generation forums? They may be more help.

What you have pictured seems to be a 2 series to my eye, ring flange is real close to side bearing, and looks to be an Auburn unit. BUT DON'T take my word for the series

No, we don't have it exposed. He's trying to I.D. it before he tears the other one apart in case he may need the spacer. I was just thinking there may be a number or casting mark that would I.D. the thing.

Thanx!!

 

Pulling the cover to ID only cost the price of the gasket and lube. Collect the lube in a clean pan, re-use it for now, and you only have to buy a gasket. :thumbup:

 

you can look it up, and no 82-92 camaro's camaros were sold from the factory with 3.73's, none, only sprots car that chevy put out in those years with a 3.73 ring/pinion was the monte carlo SS, sorry but they are aftermarket gears, they didn't even sell a single camaro with 3.23 without it being a posi carrier, not trying to act like a butt, you should look it up if you don't believe me

 

I havent seen it yet, but he tells me it may be from something like a 2.50 or 2.73 gear. He wants to put it in his 3rd gen which has a 3.73 open diff. I'll get a good look at it tonight and some pics to post.

Edit: Pics

Looks like a Auburn gear unit.

 

my87, we did look it up and I find that the info corresponds with what you say. The problem is that we know the original owner and the car and he never changed it. This is irrelevent anyway cuz we know without a doubt that the gears are 3.73. Just don't know what the series the posi unit is in the pics and therefore don't know if a spacer is needed.

prostreet, can ya tell what series it is by the pics?

 

my87, we did look it up and I find that the info corresponds with what you say. The problem is that we know the original owner and the car and he never changed it. This is irrelevent anyway cuz we know without a doubt that the gears are 3.73. Just don't know what the series the posi unit is in the pics and therefore don't know if a spacer is needed.

prostreet, can ya tell what series it is by the pics?

I can't tell by the pics,When I get to shop in the morning I will see if I have any 7.5 carrier's {I'm not sure if I have any} and take a measurement on the ring gear flange and maybe we can figure it out.

Set your's on the bench,as if the ring gear was on it and the teeth are facing you. Measure from the bench to the ring gear flange. Try and be as accurate as you can.

I will let you know what I find in the AM.

 

There are no other stamps on the RG than just the ratio?

 

I have a open carrier that is for 342 and lower ratio's, It measure's 2" to the ring gear flange. Hope that helps!

 

I found a carrier for the 308 and down and it measure's 1 11/16 to the ring gear flange.

 

Okay, if you look at the pics you'll see that I cannot measure TO the flange because it is different thicknesses. But, if I measure from the bench THRU the flange TO the mounting surface (top of the flange) it is 1 11/16". The flange measures about 3/8" thick.

Cobalt, as I remember it had 3.73 stamped in the end of the pinion and 41-11 on the ring gear. That equates to a 3.73. I'm starting to think we'll need a spacer.

 

Okay, if you look at the pics you'll see that I cannot measure TO the flange because it is different thicknesses. But, if I measure from the bench THRU the flange TO the mounting surface (top of the flange) it is 1 11/16". The flange measures about 3/8" thick.

Cobalt, as I remember it had 3.73 stamped in the end of the pinion and 41-11 on the ring gear. That equates to a 3.73. I'm starting to think we'll need a spacer.

Most aftermarket carrier's have a thicker flange,the thickness don't matter. What matters is where the face of the ring gear flange is located. It does sound like you have the 308 and higher case and will be needing a thick ring gear or spacer.