I'm with ya on the fact that it would be an awesome vehicle to have a Denali awd and have considered on a few occasions to try a Dmax into my truck but for the amount of work involved i believe you might possibly be better off adding the Denali front clip and interior into a 2500HD with a factory Dmax... sorry to rain on your parade but the idea above is what I'm doing for my next truck

 

the short sport side box may be a slight problem for a 5th wheel hitch to fit. the hitch I use could not be operated in side the narrow bed and most 5vers would hit the bed sides on a turn. just My 2 cents

 

for all that work i'm better off dropping in a P-pumped 4BT cummins.

less weight and cheaper to mod