How are they bogus? And when did you compare a 1991 F-250 M/T w/ the 300"er to the 1985 F-150 M/T w/ the same engine?
Edit- Here's the
test data btw. The 5spd/I6 49-stater pulled 28mpg over
thie highway cycle and 19mpg
over the city cycle. The 302 V8 pulled ~19-23mpg highway depending on options (manual versus auto, FFS versus FI), and the results seem to be in line with what you get in your F250 auto (IIRC). Course 50mph average speed isn't typical of a modern highway, but that doesn't mean a 85 F150 couldn't w/ the I6 couldn't pull 28mpg@50mph or that a F250 w/ the same engine
and gearing couldn't see ~25+mpg at the same speed. It also doesn't mean a modded version couldn't see the same mileage at higher speeds. In fact, if the OP can drop the same gearing in their truck, maybe fiddle w/ the fuel system too (for some reason 49-state FFS tends to get way better mileage than early FI, especially CA spec FI), they should be able to see ~25-28mpg at speeds higher than 50mph depending on how much they can drop the Cd. And they should be able to pull it off for a lot less than fifteen grand.