Ok, so right now I got a peg leg rear end with 2.73's... I just bought a rear end out of a 1988 or 1989 camaro that had posi, but I know it has stock gears. Did all the posi rears out of the 3rd gen camaros have 3 series gears or what? If some had 2 series, how can I tell because I want to install 3.73's, and I didn't want to spend a bunch of money on a new differential when a friend had a full posi rear in better condition than mine, and for only $90... so if I buy the gears, I need to know if they will even fit into the existing carrier.

Can someone help me?

3.08 and mumericaly lower gears are 2 series and 3.23 and up are 3 series

lol well I knew that... thanks for the response, but I was more or less referring to the actual gears themselves... I guess I could tell if it's a 3 series or a 2 series is by spinning the pinion gear and see how many times it takes to turn the wheels, or the other way around??? Cause I bought this rear end not knowing what gears it has... all I kno is that it's a posi rear out of this guys 3rd gen, and he may or may not have put in different gears...

OK well 2 series gears are thicker than the 3 serires which is why you have to use spacers when interchanging

No, 2 series gears aren't thicker.

The deal is, the lower the numerical ratio, the larger the pinion. Don't forget, the gear ratio is not only the ratio of the tooth count; but also, it's the ratio of the diameters of the gears. So since the ring gear diameter is constant, then as the ratio moves up or down, the pinion diameter must change.

The flange for mounting the ring gear on a 2 series carrier is farther from the pinion, to accommodate the larger pinion, than it is on a 3 series (or a 4 series, in models of rear that have such a thing). That's why you can use a spacer to put 3 series gears on a 2 series carrier, but it's impossible to do the reverse.