how can you find out what rear end gears you have...no RPO sheet....its a 83 camaro originally a 6 with a lg4 and a th200c...can you find out by opening up the rear? i need to replace the fluid and gasket too

Yup, just count the teeth. Also, the ratio is usually stamped on the edge of the ring gear, although it won't say "3.73" or anything like that; it will say "11 41" which is 3.73 (41/11 = 3.7272727272) or "15 41" which is 2.73 (41/15 = 2.73333333) etc.

Expect 3.08, which would be "12 37".

how can you tell by the teeth..are thee like 2 gears and 1 with 11 and 1 with 41

That's it... in the example, 11 on the pinion and 41 on the ring...

like he said... just check the # of teeth on both... and divide the # of ring gear teeth by the # of teeth on the pinion