Yeah the Dura/Allison isn't all bad. I've just been in too many Cummins rigs w/ 300,000 + miles on them, and they still purr like kittens. The Dodge manual tranny is pretty bulletproof as well, although the automatic's seem to have issues.

If the Duramax show's some longevity they might be worth another look.

As for non-diesel trucks I'd never buy anything other than a Toyota.