Whats a good gear for a big block Chevelle that produces about 525 horsepower and is in a 4200 pound car? I have a Turbo 400 tranny and I'm looking for a gear ratio that will give me good performance at the track and on the street. I drive this car to car club meets, but thats rare. I would like a 4.10 or a 4.56. How do these gear ratios react on the street? I'm hoping that someone has done this before and I don't have to make any mistakes. It currently has a 8.5 10-Bolt rear end with 3.42 posi, but it's not enough.