changing diff ratios

[hegenderfer]

Cool site! ok, I have a 1978 F250 Supercab 2WD 400 ci Auto, the Differential is a DANA 60 and the lowest pinion swap I can find is 3.55. Does anyone know if I can use a different differential assy axels and all that would allow me to go to a 3.08 for gas mileage? Currently running a high ratio, 60 mph is 2400 rpm, would like to see 1800 or less rpm at that speed.

Thanks! Ben