[Campy]

I have a Ford 9" as well. I do not use any other lubricant other than the 80/90EP gear lube. I have not any issues with excess vibration or noise. You should be aware, however, that in the Cobra, you’re sitting just 12 - 18" from the rear end and you will hear a little more than in other vehicles.

On a side note: When I was in the build stage, I purchased the entire 9" rebuild kit with new gears, etc. I seriously considered doing the job myself. That was at least until I did some reading and discovered how critical gear lash tolerances, end play and other adjustments can mean the world of difference. Especially in the longevity and quietness of your finished differential. I located a local shop that specializes in all types of rear ends. $125 later I had a like new, freshly painted setup. So far I've got 2500 miles on it and it actually quieter that when it was first installed.