in my old 76 dodge aspen i would get about 24-26 on the highway. it was the super 6 and I drove it like an old lady, i wasnt gonna get anywhere fast anyways. if i got about 70 mph though the mpgs sank like a rock to around the 15-17 range

From my experience, the more worn out your /6 is, the better the mileage will be.

I guess I should mention that the 904 is in need of a rebuild and a shift kit. It shifts very soft and the front seal is leaking a bit. Never slips gears, though. The tc may be shot too.