There's a reason everyone else uses the Cummins for the repower. The Duramax doesn't hold up the way the Cummins does and you'll have a hard time convincing people otherwise IMHO. ...
just because that is the case doesn't make it true. it's a rep, just like anything other rep, it's not founded on actual truth.
you just have to compare apples/apples:
since there was no d-max until the end of the 2nd gen 5.9, i'll have to agree that the 5.9 was probably a bit more reliable - but not by much: the early d-max had injector and major cooling issues and the 5.9s had failing lift pumps that killed the IP. [since the d-max came out in around 2000, you
just missed the end of the 53 blocks that would crack for no reason, otherwise the d-max would get this round.]
the next couple models of d-max had better injectors, but had head problems and sensor problems. well, the first year of the 3rd gen CR cummins had a ton of ECM and sensor problems as well. i say it's a wash.
the next d-maxs got better, and so did the '04+ CR cummins. i'd say 'wash'.
then the 6.7 cummins... there wasn't much that worked
right on that motor for a while. d-max is the hands down winner for this round.
i'm just pointing out that reps aren't everything [ford 6.0s are all lemons, right? well, my 'invincible' 7.3 had me stranded
thrice and my 6.0 hasn't had a hiccup]. pit a 12v cummins to a late model d-max - not a fair fight for the "who's going to leave me on the side of the road" game. cummins won't have sensor issues, but the d-max is unlikely to go down for an overflow valve, stuck DV, stuck injector, etc.
it's all a game. i'd like to see a d-max in a deuce because i think it'd be BA and would probably haul like a mother'.
all that said;
my repower project is a 5.9 cummins.