Originally Posted by RonSSNova
Advisable, especially with a stick.
Basically a simple rebuild with clutches, seals and C6 Z06 axle stubs. A 3 rib case is preferred, not sure if the 99 had one or not?
If you can do the work yourself, not even too expensive.
3-rib cases started in '01+, so he has the weaker single rib. I cut a best of 1.54 after ~150 passes with the stock rearend and just a 4.10 gear swap before the driverside output shaft sheered, which I believe is just a matter of time with metal fatigue. I put in a 300m shaft and another ~150 passes and no issues with a best of 1.49 and went 10s as you can see below in my sig. Though I had less power and more gear which helps match rpms and wheel speed faster, clutch slippage to take the strain off the drivetrain is going to be key to making it last as well as not dead hooking or having wheel hop. The latter I found best avoided by running a biasply tire, hope this helps.