problem with gears PLEASE HELP

[eurokiller]

I recently bought 3.73 gears off of ebay for $60 and I bought an lsd from slp. When I got both of them they didn't fit together. The hole for the bolts were off slightly. First, I thought that the person on ebay ripped me off, so I took everything to the shop to find out what size the ring and pinion gears were. He said that it looked like the lsd was wrong and the gears are right.( He took off the cover and measured the distance between bolts.) My question is how do you measure the size of the lsd and ring gear, and what size is our rearend suppose to be. I think it is 7 1/2. Thanks

[DominusEtDeusNatus]

There are 3.73 gears made for a 2 series carrier. Maybe you got those. The series of the gears doesn't match the series of the differential. One of them seems to be 2 series.

[eurokiller]

When I ordered both of them they were suppose to be for a 3 series carrier, but I bet the gears arent because I got them off of ebay. Do you know how to measure them or how to find out if they are 2 or 3 series

[DominusEtDeusNatus]

Richmond is the only brand that makes "thick" cut gears. 3.23, 3.42s, 3.73s for 2 series carriers. Are those Richmonds you got?

[eurokiller]

They are gm gears 3.73

[eurokiller]

Could slp have sent me a 2 series limited slip differential on accident? I don't see any of them on the web site, but don't some trans ams come with 2.73 gears that would have a 2 series carrier? How can I tell if my lsd is 2 or 3 series?

[DominusEtDeusNatus]

You should call them. It's hard for anyone to guess what you have. I have a pic in my gear install guide, in my sig, of a 3 series torsen. You can compare them.