[Alex V.]

I think that mileage exceeds the capabilities of any SBC, in a vehicle like your truck. Now, take the Vortec 350 in my dad's '97 Suburban that would get 20-21 packed with 5 people and luggage on long trips and put it in a vehicle light and small enough, then maybe - but not in a truck.

I'm not familiar with the Toyota engine but I think you could potentially get those kind of numbers with the right diesel... but it ain't gonna have 300 horsepower. I want to put a Cummins 6AT (3.4L Onan design) in a 1/2 ton Suburban someday.