I bought a 1999 Jeep Grand Cherokee for my son. It has a build date on the door of 8-98 The transfer Case selection bezel shows 4WD full time, N , 4 low. But I decided to try it and I find 5 selections. the N section is not natural. IS this normal or does this have a different TC in it? I also need to change out the front wheel hub, now I'm not sure if it is an 98 or 99. the title says 99

 

It may have a NP242 in it. There'll be a small metal tab on the backside of the transfer case that will have the model stamped into it.

The Wheel Hubs and Brake Rotors need to match, so if you're replacing both, you can go either route. If you're only replacing the hubs, the only way to be sure is to pull a rotor and measure it. Rockauto.com is great for stuff like this. If you click on the blue part number along the left hand side, it will show you all the other models that used that part...

 

But do we have any choice? Very few vendors know/accept/understand/believe/care that they changed in '98/99. Quite a few XJ's (&, presumably ZJ's) with odd hubs/rotors.
Distilled from what I take to be the definitive guide (borrowed from whoever posted it in NAXJA):-

"2) Older type unit hubs ( Jeep Part number 53007449 ) used 1990 through 1999.5 ( Use Composite brake rotors).
3) New type unit hubs ( Jeep Part number 5016458 ) used 1999.5 through 2001 ( Use Cast brake rotors). .

Composite rotors should have a rounded off corner at the wheel mounting surface and look like two pieces joined together. Composite rotors have a thin sheet metal like appearance at the holes where the lug nut studs come through and measure about 1/8 "(.125) thick in this area. Composite rotors have an overall height of 3 3/16"."
"

 

I took it to the shop. Yes has 242, the wheel hubs don't make noise but the shop hears it when turning. They are going to swap them out anyway. Not sure what the grinding noise when turning is, they agree it sounds like the front right side hub. I guess I keep replacing until I find it.