i sure see what you are saying about changing the rear gearing. that would be the biggest bost to milage no matter what engine you are running. some v8's would be able to handle the taller gears better and make some of the smaller sixes seem pretty puny and might get better milage to boot. but for how these trucks were originaly built i still doubt a 350 gets better milage than a 250 with everything else the same. yes, if you insist on flooring it at every light and drive 70 down the interstate, maybe your right. my 64 shifts into 4th gear at 25mph and milage seems to be best at 35 to 40. i rarly drive over 52mph. that's what my truck was designed to do and i realize i am in the minority. why would chevrolet keep around these gas hog sixes for all those years after '55? they were always listed as the economy model.
