20mpg in a 2.8 B2?
Never happen. I had a 84 with a reman 2.8 and c5 trans with 235/75-15 tires that got 15 on the highway if I kept it below 65 mph. This thing ran as good or better than it did when it was new. The 2.8 autos were only 3 speeds with no overdrive.Around town it would be a decent driver but I would never...I repeat, never use one again for highway driving. My 90 B2 only gets 12mpg on the highway with OD.
If your lookin for a beater truck with hopes of good mpg I would look for an older F series with a 300 in it or a 2wd ranger.