I have a 1976 Stingray, L-48. April, I am going to install a 430hp 383stroker. I currently have a Turbo 350 trans, I believe in there, with a 3200 RPM stall speed, and a .308 rear end, taching 3100 at 70. Anyone have this trans in a 400hp+ vette? Is it worth the upgrade? Difference in gas mileage?