GM stopped building the 2500 PU in 2003, and that was a extremely versatile truck. I just traded mine in (214,000 miles) on the 2500HD and wish GM still built the 2500 (8600 GVW) version -- I'd ahve bought it again instead of the 2500HD.
GM has only built the 2500HD version since 2003, and of course, smaller niche, so we don't get it anymore. I suspect if more people drove it (very smooth ride compared to the 2500HD and the F-250) that niche would grow quickly. And with its 6.0L had no problems hauling my 3200 lb camper, including climbing the Rockies numerous times.
Same thing happened to the best van ever as well -- that Safari/Astro was it, and it stopped production several years ago ... and much better van than the mini-vans now more like station wagons. And its AWD system was excellent. But once again, a small market.
Guess we should have started a small market vehicle building business years ago and captured that niche market from all the Big Three (or is it four, or five now) ... and combined it into a 2500 and Mid-Van company. We have gotten them all - but probably a huge headache with it... :) :) :)