They're all 6.6's. You need to find out what generation. 07 in the pickup world is an LBZ, which is good. Who knows if that holds true for these though.
The engine is van based. So in theory less horses, but the downfall in this application really is going to be the rear end.I've worked on a few. Honestly no different than a Silverado engine wise. The Allison trans is pretty bulletproof. No idea about brakes and suspension stuff though, I would assume expensive though