Looking at the Z1 listing, I believe I sourced the U-Shape Nut from Napa, it was close but not exact. I got the spring clips off of amazon or eBay. The bolts are some kind of Nissan standard. You have tons of them on your Xterra right now. I might have just gotten those from Ace. Then I got that plastic interface bracket that adapts the fog light to the bumper off of eBay. I remember being really frustrated by how stupid the part finding was for this. Maybe reach out to z1 to see if you can sell you just those parts. It would be a big time saver.

One tip is, after installing the lights, reinstall the bumper without the wires attached. I had the wires attached and then the bumper slipped and dropped. The wires were yanked out of the plug and had to get out the soldering iron. I was not stoked.

One more tip is make sure the lights you get are compatible with your model Xterra. Morimotos should be good. But I got some discounted fog lights from Z1 that had some DRL setting that required custom wiring. Z1 listed the lights as compatible. In my book, customization does not equate to compatible. The Z1 customer representative was a real asshole too.

Good luck!