The ideal bearing to replace them with will have the following ID's in the full part number (NSK numbers quoted).

**** DDU # L22 - HKPM.

the *** is the basic bearing number which is defined by the Bore and OD of the bearing
The # may or may not have an identifier there.

The "DDU" is a double seal, the "L22" is to do with the bearing fit and the "HKPM" specifies a high temp grease pack (not the highest temp - only up to the temperatures our bearings will see).