There aren't too many "kits" out there but there are so many options; like guys said links and coilovers or leafs. Also, there are a ton of options for axles, dana 44s are just the start. Are the 44's fully built with gears and good 3rd members or just the housings? Do they have good shafts? Are they Chromoly? Would you ever need Chromoly? What about brakes, are they drums? Do you maybe want to go the extra mile and install disc? What about driveshafts, do they need to be custom? Then you have steering and so much more. There are so many questions to ask when going SAS, so many!! I would create a massive bullet list of questions to ask then start addressing them one by one.
I would give a few shops a call and explain your goals. Shops like Ruff Stuff, All-Pro Off-Road, and a few actual installation shops would be a good place to start.
Cali Fabrication in Sacramento along with Stellar Built in Sacramento have performed their fair share of SAS builds and sometimes it helps to talk to guys actually installing the parts, not necessarily selling the parts. Phone/sales guys are completely different than installers.
Call Stellar Built:
Stellar Built - 4x4 Fabrication Shop Sacramento, Custom Off-Road Builds
Just my 02.
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My 4Runners; 1999 SR5 4WD Jade Green, 2014 TEP KDSS White, 2016 SR5P White, 2016 TEP KDSS MGM (Jade) and 2023 SR5P on Portal Axles.
Trail 4Runner (5th Gen 4Runner Mods):
Trail4R.com
6th Gen 4Runner Mods
https://6g4r.com/