Hello there I have a 63 3/4T Chevy that my Grandpa bought new and was given to me by my dad. It is all original with a 292 and a heavy duty 4 speed. My Question is other than changing the rear end is there any thing I can do to increase the fuel mileage and the fact that I am afraid to reach highway speed because of the RPMs, but still keep the low end power. I also thought about putting a front end under it to make it a 4X4 any good advise? Thanks for the ear.

That inline 6 cylinder still has carb and points/condensor. So an electronic ignition could help gas mileage and maintenance. axle gears would be easy. You know going 4x4 won't help gas mileage. Not too many factory 4x4 in 63, maybe not even a factory option back then. I don't remember seeing a factory one. But that would be a hard converion, you'd have to come up with a front differential that would fit that frame, drive shaft, transfer case, actually you'd have to change the transmission to.