After seeing some internet rumors about HD Tundras, some with Cummins V8 diesels, DRWs, etc, I'm wondering: Do you know anything official from Toyota? Do you have a link?
Google 5.0 Cummins V8 Toyota and you will find a number of reports that state it will be offered in 2016. I am almost positive I read a formal announcement in the past, but can't find it now. All the articles seem to be from early 2014.