Ok, can someone please help me, what's the difference between a 2500 and 3500 in the 2007 model.

 

Well for one the 3500 with the long bed you can get a drw. but i'm going to assume you mean something like a qc sb srw for both. The 3500 has a little bit beefier front end suspension and the rear springs have what is called an "overload spring" other than that engine tranny all the same

 

Well i was just wondering because the towing capacity of botht he 2500 and the 3500 are the same....

 

A 2500 CTD auto with 4.10 gears can tow 12,950 lbs. A 3500 CTD SRW auto with 4.10 gears can tow 15,850 lbs. How is this the same?

 

Because looking one the dodge.ca site, it says for both 2500 and 3500 towing capacity at 16,400lbs

 

The only difference is the rear leaf springs. Everything else is the same.

 

when I bought my 06 2500 dealer told me same thing that rear leaf springs were the only difference

 

The only difference is the overload springs on the 3500 SRW. All other components are exactly the same.

 

There is way more involved than just an extra leaf spring...i cant believe you would hang your hat on what a car salesmen told you one time.
3500 QC SWB is equiped with cummins standard. Both auto and man have extra spring and a AA11.5 rear axle 3.73/4.10
2500 QC SWB G56 manual comes with AA11.5 and one less spring. Optional cummins.
2500 QC SWB 48RE auto comes with AA10.5 and one less spring. Optional cummins.
Think back to before 2002... same difference as Dana 70 vs Dana 80
Also, the 4X4 3500 has bigger front springs than the 2500 kid brother.
It also depends on the wheel base...long bed, short bed, single cab or megacab
My 2007 3500 2wd 5.9 G56 megacab dually has one less leaf spring than my 2006 3500 QC 4X4 SWB. They have the same axle, same motor, same gear ratio.

 

oh yeah...food for thought
you can move to Texas and register as Farm and haul as much as the trailer can haul legally. i.e. i have a 30+5 dual tandem dovetail that is rated for 22.5K lbs. i can haul it fully loaded with either of my farm tagged trucks mentioned above.