I would recommend ford racing brand gears. That's what I have, when I replaced my gears I used royal purple gear oil upgraded to a locking differential and replaced the bearings in my rear end as well. If you already have a locking diff, its a good idea to replace the clutches in it while its apart, the difference will be night and day better.
I agree with the ford racing gears. Cheapest I found the gears new was buyfordracing.com. Pick up a master bearing kit from somewhere like american muscle and bottle of friction modifier. I used royal purple for the rear end and have no whine.
A forum community dedicated to Ford Mustang owners and enthusiasts. Come join the discussion about performance, builds, modifications, reviews, engine swaps, classifieds, troubleshooting, maintenance, and more!