Converter and gears, my 64 all steel savoy with a 73 440 stock pistons, 509 cam, torker intake, 750 Holly, stock 452 heads, TA 3800 vert, 4.88 gears, 14/32 slicks ran 7.50s all day. My 60 was in the 1.60 range and run regular pump gas (8 to 1 ratio pistons) done at 5000 rpm.