Best late model engine for conversion?

[freemonty]

Hey ladies and gents,

All the business with my radiator leak and the fact that my 350 drops about 2qts a month on the asphalt has me thinking it's time for a motor swap. My truck is my daily driver so I like the idea of a fuel injected 6 cyl with an overdrive. A late model 6 should make plenty of power, probably more than my 350... and with an OD I could maybe get 15-18mpg?

Does anyone have suggestions on a widely available, reliable GM motor that would be an easier swap? Is a fuel injected conversion SIGNIFICANTLY more expensive than a carb?

Chances are I'll end up with whatever engine I can get my hands on, through wrecks and donor and stuff, but I'd love to hear your thoughts.