Hello all, id like to start by saying this is my first post here, not that it matters but i figured id put it out there. Any way, i am currently restoring an 81 camaro and the guy i bought it from tried to make it a drag car. So instead if having the stock 6 cylinder and 3 speed, it has a 454 and a th400. So obviously this guy wasnt afraid to change stuff out to his liking. So this leads me to the main topic, because i was looking for the serial numbers on the rear end. Now, from the factory it was a 2.73, and all 2.73s to my understanding are open diffs, but this rear end is an LSD. It is a 10 bolt, but has a chrome diff cover, so it isnt stock. But also, it had this serial code: 2 PW G81751. I looked online for a good 30 minutes and couldnt find anything matching this code. For now, this is all the info i have. Could anyone fill me in or point me in the right direction? Ill try to get more info up tomorrow but until then this is all i have. Thanks.

 

Looks like G81 is a posi.
http://www.differentials.com/gm-axle-ratio-identification-codes/
Here ,have fun... Chevy Camaro Rear Axle Information & Restoration

 

only real way to tell for sure is pull the cover.

 

Just because it has a chrome cover doesn`t mean its not stock. Like the others says pull the cover ,And if you don`t know what you are looking for ,Have someone who does ,Even if you have to take it to a shop. <and maybe show a picture

 

If you raise the rear tires off the ground, rotate the tires 1 revolution while someone counts how many revolutions the pinion flange goes around that will give you the ratio if it's a posi..

 

Ok, so i pulled the cover today and it has richmond gears that are 3.43 ratio gears.

 

now you know
be sure to add the posi additive when you add oil/grease if it is a posi

 

Depending on the type of posi/lsd or what oil he uses, he may not have to add the additive. Only clutch type LSD need the additive and most good gear lubes have the additive already present.

 

Yea, ill make sure to put the right fluid, and ill look into whether or not i need the additive.

 

I have a numbers matching 70 SS/RS. I know everything is original because it was my fathers car and he was the first owner. I am getting ready to do some work on it and need to know the ratio on the rear end. I crawled under and got the code but I’m not sure about it. If anyone has access to codes, it is COT 0331G 1
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