I have a 10 bolt rear right now. will the gears out of a 1998 for mula LS1(3.42's) fit in my car? thanks!

Alot of the 305/auto combinations had 2.73 gears, and if this is what you have, then No, they won't fit. 2.73 gears are bolted on a "2" series carrier. The 3.42s, if stock, are bolted to a "3" series carrier. The reason I say stock, is because Richmond Gears makes 3.23, 3.42, and 3.73's that will bolt to a "2" series carrier.

are there any vins or anything i can check to see what stock gears i have? right now, i have 3.23's but i am pretty sure they are aftermarket