Just a regular ARE cap nothing special not work one or anything and only used a bit during winter
Eibach everything is what i wanted ideally (just waiting on the postman) usual eibach backorder. I've ordered Eibach front shocks and eibach front springs was just about to order stuff for the rear
With stock springs, you can expect a drop of 1" every 400lbs
Eibachs provide 10% stiffer springs compared to stock and they're 1.5" longer as well compared to stock. If you're into offroding you want longer springs. They will provide 1" lift over stock height, so using what we know from the factory springs it'll take 440lbs to drop them one inch. Eibach rear springs are linear, they're not variable rate. verified by Eibach.
TT springs are for the most part shorter than stock , Most of their line feature linear rates though they have 2 versions that are variable rate. 1223VT is the only one i'll look but it'll be at the very last of my list of choices since they're only .25" longer than stock. Again my theme is offroad so i don't compute installing items, in this case Coil springs that are shorter than stock. But I'd recommended them for work trucks though cause you don't need to thinker with shock lenght, and having a heavy linear rate they don't move much (say you went with 1211's or 1223's you'll only sag them 5/16 with a 200lbs cap) They'll run with the stock shocks, they have a few different selections, 1210's are 25% stiffer (516 lbs per inch), TT1223V or VT are 35% stiffer and variable, but only the VT is 0.25" longer than stock, the other is shorter (560 lbs per inch) and their HD springs (TT 1211, and TT 1223, 638 lbs per inch).
Icons 1.5" are also 1.5" longer, but they feature progressive/variable rates that change with load. Icon only advertise they're 75% stiffer than stock on their 2nd rate. Their 1st rate is softer than stock, they used to advertised 25% softer than stock. I don't know what rate they hold in between the softer and their heaviest rate. I ran them with 500lbs of permanent weight and i ate 1" out of them, i was still still lifted 1/2" over stock. They don't sag like linear rate shocks once you reach their next heavy rate (they'll switch to 360lbs/inc each, so that requieres 720lbs to drop them one inch).
I'm running even longer than Icon springs, Clayton 2.5" springs, mostly cause i didnt want a spacer in my truck (i was running 1" spacer to recover the 1" i had lost with the extra weight using Icons), and i wanted longer offroad shocks (i'm running 28.75 extended shocks now compared to the 25.5 stocker) with something that could support weight. In this case the Claytons are not RAM specific but they came from the 2020 Jeep Gladiator aftermarket and are perfect in my case for expedition tasks. they advertise 3 spring rates: 1st rate is softer than stock, 2nd rate is 35% stiffer just like TT coils, 560lbs/inch, and a 3rd rate 75% stiffer like Icons, so 720lbs required to drop them 1 inch. you start with a 21.5" spring as opposed to the 18.25" ones, and without weight i'm sure you'll go 2.5". Icon and Clayton seem to have very similar rates, mostly cause i'm eating almost a full 1" from them with 500lbs in the bed, and i still have a full 1.5" lift.
Normal 500lbs of extra weight in the bed
2020-09-27_06-08-00 by
RAM RSM, on Flickr
This how much they sag with 1600lbs, never felt my bumpstops on the fwy, they feel much much better than the stockers ever did with weight, granted i don't have stock anything in the back of the truck anymore so all of those aftermarket parts also contribute to a better ride under max weight.
2020-07-21_04-47-49 by
RAM RSM, on Flickr
Sorry for the long winded reply. I get carried away with this chit sometimes. Later i can use what i wrote to make a similar reply but way shorter
Hope it helps.