Another opinion re: gas vs diesel.
If I were buying new now, it would almost certainly be gas. Both engine types have improved greatly in the last 10 years.
In 2006, there was more difference between them. Diesel: spend more $ and get the power and torque so that one never has to even consider not having enough. And hold its value much better. Gas: significantly cheaper - and you get what you pay for.
In this one persons considered opinion, the 2006-2007 Duramax LBZ diesel + Allison 1000 transmission was The Best Power Train that had ever been available in a light duty truck. Worth the money to me, and it provided 13 years of trouble free service over some of the roughest terrain imaginable. (also worked well for the world famous Grand Whazoo)
That truck was also a jack rabbit. If one were so inclined to stand hard on the brake, spool up the turbo charger and pressurize the transmission, then drop the brake, the result was over 100 feet of twin strips of rubber (and some neck pain for the un-prepared).