I have gotten a few *** with questions about my diff, it was built at Woodhouse by Mark Jorgensen and the price for the complete unit (built with a used Gen III case-same case as Gen IV) was $4998. It has about 5000 miles on it, mostly lapping days which is not abusive to the diff. I feel it works better than new bcz it is broke in. Works great and is smooth as butter. I feel it can easily handle the 700 HP of my car.