I use Mario Ruiz, all he works on is Detroits and he knows them inside and out. His # is 561-635-1963. He is also training his son and his # is 561-602-8312, if Mario Sr doesn't answer try Jr. We have been using him for several years and have been very impressed with him. We had our 671's rebuilt by one of the big guys in Nj and they never ran the way I felt they should and they smoked on start up. After running them like that for 1,700 hrs we decided it was time to do them again and as soon as he got into them he told us what the problem was. The big name guy used liners for non turbo motors, after he rebuilt them they start immediately with very little smoke, which I thought was hard to do with Deteroits.