Can you replace just the all joints on these LCAs?You should be able to see if you have KDSS by looking down the framerail of your GX and seeing if it has the pumps/lines. Photos of the KDSS system should be avaialble on Google. You might also be able to put your VIN in, either at a dealer or online Lexus parts website, and see if it pulls up KDSS or non-KDSS LCAs.
Regarding the alignment cams, they are dealer-only parts but are readily available. I replaced around half of mine on my MO GX at 135K. I'd be very surprised if at least some are not seized. If you need to replace everything it is relatively expensive. I just ordered the parts for an '07 4Runner from my local Toyota dealer and they fit fine. Make sure the shop coats everything in anti-seize upon assembly to reduce the chance of them seizing again. Annual alignments will also reduce the chance of seizing as well.