If your mopar is you daily driver!
My '74 D100 is my daily driver and I'm 22. The MPGs are like 12-14 ~ just normally running around town. Not really sure on highway. I know it does 14+.
what will the Mopar enthusiast look like in 10 years? like me, 10 years older. lol.
O/D 4 speed and a slant with a small turbo is what I suggest. push like 4-5lbs and gain some gas mileage. it can be done on a very tight budget. but as everyone is saying, the rest of the parts outside of the tranny get expensive