Has anyone any information on a Fairchild XP 3 mon

It is from 1958, and apparently is a moving coil type. Some information about it is provided at the Cartridge Database site (search under "Fairchild" in the drop-down box listing manufacturers):

http://www.cartridgedb.com/

Also, you'll see an indication in this article that it evolved into the Model 230, which is also listed at cartridgedb.com:

http://books.google.com/books?id=CwsEAAAAMBAJ&pg=PA18&lpg=PA18&dq=fairchild+xp3+cartridge&source=bl&ots=gB74GKw3wa&sig=Nwj4TEm0Y2rHFDZHB-W8kuSDgp4&hl=en&ei=-B29StGwOIralAeKsrB6&sa=X&oi=book_result&ct=result&resnum=3#v=onepage&q=&f=false

Regards,
-- Al

Al; Very, Very helpful. Thanks so much. Dennis