1) X hubs
Both autos and manuals are made by Warn.

2) F350 hubs
New super-duty hubs also made by Warn. They use pulse-vacuum technology to engage and disengage. Basically an auto hub that engages instantly and you don't need to back up to disengage. You can also manually engage like regular hub. Pulse vacuum system is integral with entire 4wd system and is not retrofitable

3) cheap hubs
All Warn external mount hubs (like Xterra uses) are basically the same. Hub body, clutch ring and inner drive gear. If a guy found a set of cheap external mount hubs off say a CJ or Toyota and replaced the IDG with one of the proper spline count... Voila!

4) Warn vs. Mile Marker and S-Winch
S-winch hubs are made by Mile Marker. Call Mile Marker and ask them which 3rd world country their hubs are being made in this week.

5) Hub Studs
A very good thing. Much more resistant to loosening than bolts. Use them. Always a good idea to check hub hardware frequently. Think every oil change.

6) Warn Premium vs. OEM Nissan hubs
OE hubs are smaller and built to tighter tolerances. Aftermarket hubs use larger clutch ring and IDG. Your choice. Both will never break with the power they will see from even a blown, locked up Xterra on 33's.

Hope this helps someone.