Different Rear axle between the 3500 SRW and the 3500 DRW trucks, leaf spring packs are more robust, (more leaf's on the DRW than the SRW truck) . Rear axle on the 3500 Dually is rated to carry more weight than on the 3500 SRW truck, it's there for the research, AAM manufacturer...Both trucks that come with same weight rated 17", E rated tires, and the 3500 dually is rated at 9750#, the 3500SRW rated at 7500#, and the 2500 even less than both of those..The basic ?? 2500 and 3500 dually have same frame set up, front and rear axles are different between the 2....The so called 9900# is now higher than that. My truck has a GVWR of 14,000#, GCWR is 37,500#...I need no special license, I'm towing my 5er for my own personal use...some laws vary state to state. In NC, you have to pay for "total amount of truck and what you tow"...ie, GCW...if pulled over to be weighed, all one would have to show is registration covering GCW, if your over...ouch...if your under you're "good to go"..that's it... Most don't use GVWR anymore, they do use RAWR...and it is based on tire weight carrying designation, but when you have E rated tires on a 2500, a 3500SRW and a 3500 DRW, all with close to, if not exactly the same weight carrying capacity, and the 2500 is less than the 3500 SRW and the 3500 SRW is less than the dually ( duh, 4 wheel's), then they are not "alike"...no matter how badly one wants to believe it.
All ratings on all these trucks are under rated to an extent...Most manufacturers don't want to have to fend off lawsuit after lawsuit for those that may have an accident due to overloading their truck...but, at what point of going over the recommended weight ratings do you become unsafe or start wearing components out on one's truck earlier than normal? I'm an Engineer and I don't know...Nor will I push the limits...If a 2500 is the same as a 3500 dually, then I could have saved a pile of money for a TV, but I purchased the right truck for the job...if a 2500 and a 3500 Dually have all that much in common, then why have a 2500, 3500 SRW and a 3500 DRW truck, all with different gear offerings, transmission offerings, GVWR's, GCWR's, FAWR and RAWR's'? No, it's there for the research...The 2500 and 3500 DRW do not have more parts in common then one would think, but that's what makes America great, some have one opinion, some have another. I'll tend to err to the side of safety, do the math, use some common sense and try to match the right TV up to what I'm going to be towing and enjoy the peace of mind. I figure the design and production Engineers know more about their product and it's expectations and limitations than I do..