I might get flamed here, but in my opinion about the only thing in the auto industry that has become less reliable in the last 10-15 years is the Diesel engines in light trucks. Diesels are regarded as long lasting mainly because of the logic of long ago, when gassers were junk after 100k miles and diesels were so simplistic, mainly due to the lack of an ignition system. Give it fuel and its gonna run. Diesels today are anything but simplistic with their electronics and 30,000+ psi injection systems. Most of the problems are emissions related.
Since you are getting a dually I imagine you are towing so heavy that a diesel may be necessary. But these days to buy a diesel solely for reliability and longevity is not sound logic, again, in my opinion.