After many hours of research I decided that a Express 3500 passenger van would handle my needs for towing a 6500 lb. TT. We went to the mountains in North Carolina and it struggled with the 8 and 9 grade mountains. While on another forum I was told that the maximum trailer weight for my 2010 was 7300 lbs. After referring with my owners manual that is what it says. After more research I found that 2010 was the last year the 3500 had the 3.73 axle before changing to the 3.42. If the 3.73 is better for towing than the 3.42 why is the towing max 2000 lbs more on the later models ( 2011 and on). Has anything else changed.

 

Around that time came the change from the 4L80 to 6L90 transmission. The extra 2 gears can keep it in the proper RPM range.

 

what engine you got..4.8? 6.0 with 4.11 would crank up any grade

 

gears/trans might be it but another thing to think about is dodge. i think they changed the gears by now but pretty much for the life of the cummins in their trucks they ran 3.55 even in the 1 tons.