Currently I have a GSR transmission and the 5th gear is starting to crunch (probably eventually grind). So, I was going to replace the synchro and gear.

Can I use the 5th gear from an LS tranny? correct me if I'm wrong, but this should get me better gas milage(highway anyways) correct?
Opinions please

 

Yes you can do so and it will drop your freeway "cruising" rpm a lot... I personally wouldn't bother in doing so... It's a sharp drop in the gearing and you will notice the motor working a lot harder to get the car to pick up... Check the gear but unless you've grinded it really hard it's most likely just fine.. If it looks bad then swap the gear and the synchro... Peace