2006-2008 BMW Z4 3.0si Differential. The differential has a 3.73 gear ratio. Will fit all 2006-2008 N52 3.0i and 3.0si BMW Z4's with an automatic transmission. Will not fit manual or M model cars. If swapping this into any car besides a 2006-2008 3.0si car, then your gear ratio will change. The differential is off of a car with 118k miles and in good running condition. It was fully tested, with no odd noises or grinding sounds. The fluid has been drained with no metal shavings or abnormalities. There is some normal cosmetic surface rust and wear, as shown in the photos. You will need to reuse some of your existing hardware for installation.