Yep, I live by my trip meter.
I know I can get about 160 miles out of a tank.
In winter with 4X4 and leaving it idling to keep the cab warm it drops off some, and above 80 (3,000 rpm) it starts to plummet.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.