52 Chevy Kid,That 23 MPG sounds about right with that gear ratio.Along with the fuel economy you should still be getting good performance.With a 700R4 you can go up to a 4:11 rear and still have good fuel economy and good pickup.when I put mine together I was gonna put in a 3:73 rear,but after the way the truck performed and the gas mileage,I just left the 3:90 in there.Way too many people changing engines,to get good perfomance and economy,when the real secret lies in the gearing.
