I recently purchased a early 99 F250. I got this truck with out doin much research and this truck must have been one of the first built. I have been getting 19-21 mpg which is better than i expected but was curious about the fuel capicity. I have read that these have 28 gallon tanks but the last time i filled up as soon as the fuel light came on and i put in 32.5 gallons with out over filling. Did the early 99's come with a larger tank?
friends 01 f250 regularly fills up with 36 gal. running it almost dry, 780 miles out of a tank. my 99f350 drw takes 36 gallon and i get around 600-650 out of a tank. You may have a problem with the pickup leaving a few gallon in the bottom. there is a section at the top of this website that shows you the fix for getting the most out your tank.
Reading this thread makes me feel a little better.. I filled up the other day after driving with the light on way longer than I should have, but I was able to nurse 40.625 gallons into her. I was thinking that the pump screwed me out of a few galons but if the capacity is 39 gal on the long beds I could see fitting another gallon or two in the filler neck.
99' PSD extended cab, long bed, 4x4, 6 speed. 4" custom built exhaust system with MBRP downpipe. EBPV disconnected. Southbend Organic clutch/solid flywheel. Goodyear Wranglers.