i have a 1956 1/2 ton with a 305/350 set up with the stock rear end,390-4?? gears, i am replacing the transmission with an 700r4 and the rear end from a 86 chevy 1/2 ton, i think around 338 gears, was getting 10-12 mpg, hoping to see 15-20 when done, any one has any idea if that is wishful thing or possible
