Steve, you can get those parts at just about any RV store. Just unbolt the 4 nuts, & your spindle nut, and bring the assembly to the store with you and they can match you up. You should be able to read the bearing numbers once you wipe away the grease. Most auto parts stores can match those numbers up for new bearings if the RV store doesn't have them. I always carry an extra set (greased up & ready to go) in a zip lock bag.
Dave & Paula