An extra spring to go from 2500 SRW to the same setup as a 3500 suspension is, to me, essentially the only observable difference. If you look closely the holes for the overload spring are there in the frame because the frames are identical. As far as load capacity, the capacity is based upon the least capable portion of the vehicle suspension including the wheels. Now I am no automotive engineer nor any type of expert so make your own determinations. For my part, after many weeks of research, talking to mechanics, consulting dealers and reading posts in multiple forums I chose to run the manufacturers numbers and give myself a bit of margin. I will not post my research but I chose to go with a 1 ton DRW to tow a 3585SA. If anyone takes the time to use a calculator they will note that comparing the DRW ratings for two tires per side to a 1 ton SRW with the same tires pretty much explains the change in cargo capacity. Note that it actually decreases the tow rating as it adds additional weight to the truck itself.
I have to say I am with bsmeaton on this one. Also, as I have said in other posts, besides civil liability there is a danger of criminal charges if a TV is found to be grossly over its specified weight ratings and this is seen by the investigating officer/prosecutor to have been a major contributing factor in a serious accident i.e. one that results in death or serious injury. I tried to locate some examples but they were all commercial vehicles.
Think things are bad now wait until GM comes out with the 4.5l diesel for 1500 series trucks.
http://www.autoblog.com/2007/06/15/g...the-hummer-h2/
With over 300 HP and 500 F#'s of torque you can tow any Montanna with this engine. Problem is that a 1500 series truck is built lighter than the 2500/3500 trucks. Wanna bet some of these will soon be seen with extra springs, air bags etc and the owners will argue they are now "beefed up" to heavy duty, the manufacturers really have underrated them so they can still sell the HD's and, ... well you all can guess the other protestations we will see in the forums.
Now that we are nicely warmed up who makes the best trucks :-P