Hi - I have a 78 F150 4x4 SuperCab. I would like to convert the rear end to 3/4 ton, and have 3.50 gears in front. Does anyone know what the highest gear ratio is available for 3/4 ton this age? I know I can't go with too much of a difference between front and back and still be able to use 4WD. Thanx for any and all advice, Tru