Need a 5vdc inductive proximity sensor

We have an old piece of equipment with 5vdc control power. One of the components is a 3-wire NPN shielded 12mm cylindrical inductive prox. I have verified that it is NPN and does in fact run on 5vdc. There are no markings on the sensor to identify the manufacturer. Problem is, I can't find any replacements with a supply voltage this low... everything seems to be 10-30v. I'd really like to find a drop-in replacement as we have about 3 dozen of these machines. Any suggestions?

Sorry, I misspoke--it's a magnetic prox not inductive.

Found one:
http://www.cherrycorp.com/english/sensors/Magnetic_Proximity/mp1005.htm