Not very good, I haven't checked it with my new dual W-1's yet, but it used to get around 16 with the single Mono-jet carburetor. When I hit the highway for a day of driving, its usually around 70 mph, so thats why the mileage is probably lower then it could be. I believe wind drag also plays a big roll in it. I got almost 20 on one trip, it was all on back roads at or below 55 mph.
I had a 3.42 gear for a while and with it, the truck was noticeably quick and more responsive, but the high rpm at 70 was terrible. My tires are a 235/75 R15 (28" tall). Right now at 70, the engine runs just below 2400rpm which is just right, to pull a hill, just give it gas, no down shifting needed.
Joe
