I can tell you this. The 6BT makes the Powerstroke (pick one) look like a tinker toy when torn down. There's simply no comparison. The Duraslack isn't even on par with the Powerstroke. Duraslacks look like gas motors torn apart.
go to a tractor pull or truck pull youll see plenty of 6bts, them other brands of pick up diesels not so much!! tuffer than a slant 6 and strong nuff for anything up to a class 7 truck!!