I've had both the Duratec and lima 2.3 and both standard 5spd trans. The Duratec gets significantly better mileage (I usually get about 30 on the highway), and has loads more power, especilly at high revs but even off the line. And is quicker to rev, so makes starting on a hill easier.
I've only got 10K miles on it though, so I can't say anything about longevity, though i haven't heard of anyone blowing one yet and they've been building 'em since 01. The mileage got significantly better after it broke in.
The only pluses to the lima is 1) it does a better job of slowing the truck down when going down hill in gear--the duratec in gear feels like driving an automatic downhill. And 2) seems a little smoother running--these duratecs are a little rattly at an idle. Neither one of these is a biggie. I'm plenty happy with more power + better economy!
Last edited by 07B2300; 08-12-2007 at 12:06 PM.