Back in the 80's my 77 Datsun truck was nearly unstoppable - 275K "the hard way"
Easily outlived my friend's 78 Toyota which died @ 189K miles. That said, I think Toyota is the better of the two in the years you list. Why only import trucks on your list?
You mentioned "off road abilities" so I assume you really need the 4x4 - though a good driver can take a 4x2 in some extreme places.
I just bought a 00 F-150 4x2 with the 5.4. Four fillups so far and I'm averaging 16 mpg - with an easy right foot. Not bad compaired to the 6 cyl mini and fullsize trucks that seem to average 18-19mpg.