The Z2 Superfly was Marzocchi's first "modern" air fork. You probably have a 1999 model. Green? It should be 80mm of travel with internal rebound adjustment.
After the Superfly Marzocchi went to the X-Fly series (most of them had the M-arch). In 2000 they also had an internal rebound adjuster, but for 2001 they had an external one. They were great forks. The most reliable air forks at the time (RockShox had crappy/flexy SID's and Psylo Race) and Manitou were never any good. Fox was not out yet.
You need a special air pump for these. They take a low pressure pump because a difference between 28 lbs and 30 lbs is VERY noticable. It's just too difficult to tune them with a 300psi pump. They aren't super easy to dial in (you have to play with oil height and viscosity in addition to pressure), but it's worth it.
Personally, I prefer the X-Fly series. I think they are the best looking forks of all time, but other than adjustment and lowers they are mechanically the same.