long story as to how I ended up with 3500 springs. When I got the truck it was set up for a 5th wheel hitch and had some really heavy after market springs in it, much stiffer than the 3500 springs.
The farm I help out at has a 97 K3500 they pull a big 5th wheel cattle trailer with and the springs were not strong enough so we switched the real heavy springs that were in mine with the 3500 springs. Worked out good for both trucks.
My truck rides much worse when pulling the trailer. My truck is a factory HD truck also, F in the vin number.
I want to get new rear shocks, don't know if that will help much or not.