The Chevy uses an extended wheelbase for long box vans. Ford and Ram attach an extra 16" or so onto the back of their regular wheelbase. The Chevy has more towing capacity because of the leverage effect on the Ford and Ram. I have a 2012 Chevy 2500 Extended with the little 4.8 V-8. I've towed about a 3,500 pound enclosed trailer (motorcycles), plus camping gear, clothes, food, etc. in the van. The suspension was fine and the trailer towed well, but the 4.8 is lacking going up hills. If you're towing 8,000 pounds, definetly shoot for the bigger motor. The 4.8 does well everywhere else, including about 15-18% better gas mileage than my old '99 2500 Extended that had a 5.0.
Vans make great tow vehicles. There's so much lockable, dry storage. We kept the bikes in the trailer (dry/security) and slept in the back of the van for 2-3 weeks at a time. My tool shelves in the van were helpful, too, but I did take out one shelving unit to make room for the air mattress. The biggest pita was unloading all my tools, removing the shelveing unit (6 bolts) and then putting it all back and being ready for work. The roof-mounted ladder rack makes a good tie-off point for awnings, too. We pull the trailer with a pick-up and a truck camper, now. I'm real glad we did it, but sleeping in the van got old (or maybe it's just
me getting old).
'13 F250XL SC gas 4x4 8', Camper & Plow packages, StableLoads, LT285/65R-18 Goodyear Wrangler A/T Adventure, 18x9 Ultra Motorsports "Phantom" wheels
'12 Wolf Creek 850 TC Coleman Polar Cub 9.2k A/C, 90 watt solar, dual propane & batteries, Maggie Rack