Gearbox or Diff conversion?
Just bought a 69 F100 with a 300 cu in 6. It has been converted to a 4spd floorchange with a granny first gear. Thing is, I don't get much speed out on the freeway without the motor reving too high. Is it possible to put a 5 speed box behind the six, and if so, exactly what type of gear box. Alternatively, would it be more appropriate to change the diff to a lower ratio?
Thanks for any help.
Leave the trans, too much trouble IMO.


