I've been running the Edelbrock Performer IAS shocks on my 2500 for over a year or so now. VERY pleased! Nice and firm on pavement, both around town and at interstate speeds, but they don't throw you around the cab when you go over bumps and heaves. Where they really shine is in the gravel and dirt... much less harsh off the pavement but still plenty of dampening across the washboard, etc. I will replace them with same if I ever wear them out.
When I first got them, I went on a fishing trip in the boondocks of Wyoming with a friend who also has a 2500 CTD of the same vintage, and we happened to be trading off driving duties. The improvement in the ride of my truck was so dramatic that he bought a set immediately upon return to civilization!
A third friend is running them on his Dakota gasser and is similarly pleased.