From:
http://www.berettaforum.net/cgi-bin/...=000710#000004
This thread indicates that a Beretta 96FS Frame can be converted to a Beretta 92 through the purchase of a 92 upper. When this is done it is also necessary to purchase a 92F (Not FS) Hammer Pin from Beretta.
96 pin is part# C55055
92 pin is part# C54946
Another person in that thread indicated they used a Beretta 96 pin and just ground down the head to allow it to work.