With proper shimming, the gears must not engage, they must run smooth, without resistance and with the lowest play possible to keep them smooth running..
Aluminum diffcups and housings..
Integy makes the housings, and
Fastlane or the
Maximizer (maximizer is the better choice, they are 7075 aluminum and are a 1 on 1 fit.. (the FLM needs some work on the shaft to make it a perfect fit)