I just installed a new set of Richmond gears in my ford 9". This is on my 68 camaro with a modified 454 cu in with a M-20 trans. I removed 3:89 gears and installed 3:50 gears to help with highway driving a little. Just finished installing them and seems to be no issues or noise fsrom the rear end, just not sure how to properly break them in.

see the Break In section in http://www.richmondgear.com/ringandpinion.pdf