hey i got a gsr tranny 3 gear usuly goes out on this trannys but i wanna know if theres a way that i can rebuilt this tranny by taking a 3 gear from a ls or i dunno any one can help me

 

Its the synchros that wear out, not the gears themselves.
You can order the sychros at the dealership for crazy money OR you can get a set of Gear-Speed sychros (usually gears 3,4,5 in a kit) and have them hold up better.

Just for reference:

Synchros would be the thin gears shown above - see directly left of 10
(note-it is not the fat inverted gears under 8, just the thin things)
So...I guess you cant really order them from a dealer, unless you buy crap you dont need)