I have the heavier 6 leaf ATS springs on my 01. after 260K miles my original ones were shot, beyond just the 2 inches of sag. I hauled a Wrangler down and a Bronco II back from a 600 mile round trip and ever since it never did handle like it had before. It never did handle like I thought it should, ever since I bought it at 214K miles. does now. When I got it I replaced the shocks (were original from factory) and I replaced the rears again because it was better but still not what I would call "right". after that tow it REALLY handled like $#!t. like the rear end wanted to come out from under, bad.
Right after I got it I replaced the ball joints. probably 10K later it got a new rack. and realigned both times with front end height checked and corrected each time (REALLY important in getting the front end "right")
I had a computer/injection issue in the 250's (250 K mile range) and got that solved, then the engine was showing its age. It became a garage ornament for a while (couple years-- TOO long) and as soon as I went on the maiden voyage in it with the replacement engine, I was reminded of the handling issue, "real quick".

so all at the same time, I replaced ALL the bushings in the front end with urethane, ("Energy Suspension") still has the ball joints I put in 30-some K miles before, still fine. I put in upper control arm bushings, lower control arm bushings, rack mount bushings, sway bar mounts and end bushings. Put the ATS springs in at the same time with another fresh set of shocks and a new set of tires. Aligned again. Have around 6k miles on it since the new springs and bushings, now it drives like it should have long ago. But those new 6 leaf springs made it ride ROUGH. I've owned a total of 7 years and have 50k on it and counting in that time (remember the time it sat)
Ive added a leaf to existing spring packs before and though noticeable, I never had the addition of a single leaf vs "stock" make THIS much difference in ride stiffness. I went by past experience in that department. But Had I known then what I know now I'd have opted for another company's 5 leaf "2 inch over stock" springs instead of these. I searched around online a bit, Ive bought leaf springs online before and had good results but I cant remember who I had gotten them from before. When I found these, I found a few choices/options listed among companies.
While I am glad I didn't go with the generic $100 a piece garden variety spring packs that many had, I think these are a bit on the overkill side of things.
Yes, they do what I expected out of them, only complaint (if any) is the extent it stiffened up the ride. I was hoping they'd smooth out a bit when they "settled" after install but so far, no. I haven't towed with it yet since the suspension overhaul, and when I do tow, it is mostly quite a bit lighter than a vehicle on a trailer, (more like a small pop up or a garden tractor on a trailer) I only occasionally haul "that heavy" of a load, as I did when I hauled that Jeep..
when I had my 3/4 ton, I did a lot of towing/ but no longer have the need very often. When I do have the need, I call my son with his 3/4 ton and trailer...… .

as far as my choice on the urethane bushings up front, I have done that before this truck before as well, and will do that again. I did the upper bushings on both my Dakotas around the same time as I did the suspension work on the Durango and they too got urethane bushings and Gabriel Ultra shocks. and I've used the urethane on other vehicles before that, even. Love those.
The body on my Durango is still excellent (it came from the South, and has only been exposed to 2 Chicago winters since it has been mine. It will be with me til it rots into the ground. whether that's 100k more miles, or 500k more miles..... I do all of my own work, and I do that work without cutting corners, expecting the repairs and upgrades to last literally "forever", I hate "redo's".

 

Volaredon did you put those spring on the stock shackles or the lift shackles? I definitely want to go with heavy duty springs. The only 2 I saw were General springs 5 spring pack or ATS 6spring pack. I will keeping look around. I keep throwing around if I want to redo the bushing in the front end. 220,000 miles it’s probably do.

 

I put the ones that came with the springs on, which appeared the same length as the stock ones were.The bushings themselves were rather cheap if you can do the install yourself. I did mile in less than a day, though my Durango being from the South made the hardware much easier to remove than one that had lived in the Chicago area all its life.... and I do have a 2 post lift of my own..... that was a huge help.

 

The Springs I’m looking at doesn’t come with shackles. So I didn’t know if I should buy new shackles or use the same ones I have. I’m able to do the spring job myself so I don’t have to pay someone else to do it. I just don’t want to use the lift shackles if it’s going to compromise the weight capacity of the new springs.

 

I wasn't interested in "lift shackles" as I was counting on the salesman's claim that it would raise the back 1-1/2-2" by themselves..... as I said I used the new ones that came with the springs... It don't show springs coming with new shackles? I haven't looked there lately, but mine came with shackles, bolts and everything. Maybe mine came as a "special"? It didn't seem a "special" considering what they cost me....
but I remember the salesman (and I think it was on the site as well) was insistent that if I bought the HD springs that they did come with.... and they did. I just used what came with though I may have been able to use the old ones, they "looked" fine but by using the new ones I also got new bushings along that way.... hafta dig for the bill, don't remember what they cost at the moment but it seems like shipping from PA to IL was ~$85 or something like that.... had them shipped to my work, the big brown truck brought them and I remember the driver complaining how heavy they were,
when you change them watch out for the bolts at the front of the driver side.... I had to drive mine out part way, cut it off and drive it out the rest of the way because the gas tank wouldn't let me push that bolt out all the way. I loosened the tank and moved it in place as far as I could and couldn't quite get it out.... so the replacement bolt went in from the other way. plenty of clearance unless I get into a He11 of a T bone wreck that buckles the frame a few inches at that point...…

 

I saw a special it was for the 1800lbs springs. I do have lift shackles with 2 holes I just don’t know it the top hole is the same length as the factory shackles. If not I’ll buy new ones. I’m definitely going with hd springs. General spring has 2250lbs springs for $169 and ATS has 2400lbs for $150