Funny you should link the seat jackers - I've been having issues with the seating angle in the 100 for years (first on my 04 LX, now my 04 LC) and just installed a set earlier this week. I'm 6ft, 190 with a 32 inch inseam and fondness for sitting a bit higher in the truck and closer to the steering wheel. The biggest problem for me is that the seat bottom isn't long enough to provide enough support for my thighs and then causes pain in my right knee and lower back. I had an 05 Tundra (DC, Limited trim with leather/power seats) prior to the LX - that seat/angle was perfect for me and I've been chasing it ever since. I figured maybe tilting the LC seat back a bit would provide a bit more support.
I ordered a set of the '2003-2021 4Runners, GX and FJ' seat jackers thinking that the bolt pattern might match up, and received them on Monday. They are definitely high quality pieces that look and feel very solid and sturdy. The door side fit perfectly, but the guide tab/pin on the console side doesn't completely match up so it's not a direct bolt in. After thinking about it for a bit, I went ahead and filed the pin off (console side only) and finished bolting everything up.
I'm still playing around trying to find the best seating position and haven't had a chance to drive more than a few miles at a time so I can't give a great deal of feedback yet. But so far, it does feel like there is a bit more support for my legs which seems to take some of the pressure off of my lower back.