you can adjust the box. i have a manual box on my 71, which i just ordered a new 16:1 from Camaro central. it's made in USA, i could rebuild mine (kits available) but my original is 24:1 i kept the manual due to no drag on engine, there are manual racks available also. so i got my new box from Camaro central today, was very disappointed due to fact box is not made in USA . apparently, they pulled info off manuf. site and did not check if correct. wasted time there!