intheburbs
Full Access Member
2500 Suburban production ended in 2014 and 3500 ran 2015-2019.
2500 you could buy at a dealership but not many stocked them. They were substantially more than a normal Suburban (also could get a GMC Yukon version too).
3500 were for fleet buyers only. You could not roll up and order one as a normal buyer. Most applications were for aftermarket upfitting with bullet proofing or for the railroad to add the attachments to drive on the tracks.
Nit-picky points of clarification...
2500 production ended 2013, 1 yr before GMT900 production ended.
First year of production for the 3500HD was 2016. The 3500HD has more than twice the payload capacity of the 2500.
The 3500HD got the 11.5" rear (I think?)
My 2500 has the 10.5" rear. American Axle, the manufacturer, rates the 10.5" to 8600 lbs, according to their literature. My door tag shows a RAWR of 5500, probably because of the springs. Next limitation would be the tires, which can handle ~6000 lbs.
My 2500 has a GVWR of 8600 lbs and a payload capacity of 2088 lbs.
The 3500HD has an 11,000-lb GVWR, 6200-lb RAWR and a payload rating of 4200 lbs.
Since the 2500 and 3500HD are pretty close in curb weights, my best guess is the 3500HD got better/bigger brakes, an axle ratio upgrade to 4.10, beefier/stiffer springs, and the beefier rear axle.