Looks like an old Z1 of some sort. 00 or 01 maybe? Check the Marzocchi web page. They keep info and pictures of their old forks.
Actually I think its either a 01 or 02, most likely 01. Earlier models I think used the bolt on style arch. Its definately not an 03/04 since they were completely redesigned by then. Could be anything in the Z series, I can't tell very well from the pic.
