Specialty Z, should arrive Wednesday. I purchased from the first batch a while back. Ended up shipping the Gears and my Quaife back to them for a safe and confident install. Lucked out and picked up a free Diff in California. I have the invoice at home (at work tonight), otherwise I could tell you specifically what they replaced. I am also going to install new subframe and diff bushings with the install. Break-in wise, I think along the same lines as you, cool downs after each 10mile run and fluid change. Good Luck, Dre