3500 SRW
Last year I had problems with the duals, some from snow, but mostly from mud when it melted. I didn't have gravel on my "driveway" yet, and eventually, the mud got deeper than the axles - had to walk then. I just got through putting 370 yards of gravel down, so maybe I'll be able to drive this year.
Oh, back to the dually problem. The duals track on either side of the front tires, so the rut you made down to the less soft stuff with the front gets wasted on the duals, they either float on the stuff they squish into the rut, or they trade off which one gets to be in the rut. Either way, you lose a lot of traction. Traction is basically pounds per square inch. With 4 tires on the back, you have half the weight per square inch as you do with singles.
Solution: Go to your local tire store and see if they have any stock rims from a 2500 taken off a rig that someone upgraded to fancy wheels. I got a pair for $20 each. You have to get the cone shaped lug nuts instead of the flat washer ones that come on the 3500. With the dually wheels on the front and the 2500 wheels on the rears, the rears track right down the rut your front wheels make.
It may look a little weird, but it works. Oh, weight in the back is also a good thing...
-cj