Old information for reference. None of these parts are available anymore.
If you have old adjustable inserts or shocks and want to donate them, contact Steve88t. I'd love to do a tear down on them.

On models with the adjustable suspension, there are 3 settings selected via a switch on the console between the seats. The adjustable shocks/struts tended to last longer than the non-adjustable ones, although they were obscenely expensive to replace. When still available, new Nissan ones cost on the order of $800. That's $800 each. They are NLA and have been for decades.

Most opted to replace them with non-adjustable aftermarket struts. At this point you have no choice. Avoid parts store units if you can.

The adjustable struts were rebuildable, Nissan used to sell rebuild kits for them. To the best of my knowledge the kits consisted of new seals, o-rings, etc. and new oil. The adjustable struts just wear out, there is rarely any problem with the electronics or motors in the shocks. If anyone has info on the kits, or has a kit, let me know. I'd love to document that. Maybe reverse engineer it?

I don't think the regular non-adjustable struts just drop into the adjustable housings. The KYB "kit" was some kind of spacer, I think. Rear shocks just need NA upper mounts.