well, I had a 3.73 in my Z 28, it was a grt gear...but we are turning 6200, my Z was turning 9000....still something in that area of 3.55-3.73....would be a grt gear for these cars...5 speed auto vs 4 speed standard in the old days...so where can we get a gear for our cars, and who can reprogram it? I have been asking everyone this question for sometime, including our friends in Germany...