i would guess your rear gear is too high, putting the engine to low in the powerband. I got 16-17 consistently w/230-3psd/3.73, best was 18.5, but that was all under 60mph. Truck was all stock except HEI. brian


My \'64\'s in the Gallery
Pictures in my Photobucket
1964 C10 Custom Cab 350/700R4
1964 Suburban 350/700R4
1979 Ford F350 4x4 400/c6