I have a 1997 LT 1 with a 2.73 and my buddy has a 3.8 with 3.08's in it.. He is getting a new rear with 3.42's... Would it be a good idea to up my gears for free to 3.08? His ride has less than 40K on it and they are both 2 series carrier..

 

it couldn't hurt, but something to consider...

you'll have to do somehting to adjust the speedo for the gear change.
and i think you'll also have to ajust the ecm for shift point ifyou have an auto (unsure of this though)...so it may not be as "free" as you thought.

and for all the hassle of a gear change, why not just go with somehting that will really make a difference...3.73 or 4.10's

 

Would you be swapping complete rear or just gears? Most likely, his rear would not be posi-trac. If just gears, it would probably not be worth the expense for that small of a change in ratio, IMO.