Yeah, the add-a-leafs are awful. I have a total of 7 leaves on each side, plus 4 overloads. I don't know the stock number of springs, but all I can say is that this truck might outdo some 3500's for rear end sag when loaded down. The ride, however, is a chiropractor special. I'm not looking forward to driving I90 to 80 to get to school and back at breaks. 1400 miles is a long way in this truck - heck 400 is a long way.
The payload is amazing, though. I've had 2100lbs. of 1 1/2" ledge stone in the back, and it just about leveled it out, didn't even sag below level in the back. One of my pics in the readers rigs shows the height, sort of.
Personally, if funds were there, I'd have airbags faster than you could believe.