I ordered Slee 6" (heavy rears) a bit back and got them on before I went out on a little expedition run with the Upstate Cruisers. The install was simple since I had J springs with spacers up front, Gen1 Slee control arms, adjustable panhards, etc. I literally dropped them in within 45 minutes. Impressions On-road: If you run your rig with gear in the rear and J springs you need to go to Slee springs (4 or 6 as your application requires). The handling improvement is INCREDIBLE. I was running down the highway and didn't feel like I was going to dump the truck when I took a corner at speed. I had about 200# of tools and gear in the rear with about 200# more in camping gear and such. I also have the liner coating so that adds several hundred more pounds. Impressions Off-road: WOW! The weight handling was a much appreciated change. I could dive off 4+ foot drops and maintain 4 wheel contact, no problem. Several times I had to get out and look with amazement as I went places I used to have severe body lean and wheel stands and was firmly planted on all fours and could even bounce in my seat and not feel any shake...just awesome. Question (may be suited for those with these springs, or slee if you see this): I am a bit stinkbug right now. I am not sure how much the rear will settle but I was curious to see if I could put my billet spacers back in up front and bring everything up to level. I could do this in a few minutes and want to see what you all recommend before I sell them off. Here is a pic of the rig...the rig in the back has Js with no spacers and 33s. I have the 6" and 35s.