my stock 3:42's never broke the spyder gears did, so I replaced with a auburn pro diff, and 4:10's go to the track 1st day it was open in 07 and broke the teeth on those gears, buy 4:56 gears and it lasted until oct 08, so I basically tore apart the rear axle housing cleaned it up and replaced with another set of 4:56's with the help of scott, when I get caught up on my expenses I'm looking to do what you are, btw what did that setup cost if you don't mind me asking