Hmmm, that's a tricky one. The cup seal is a run of the mill spyder/raptor/avenger/just about any blowback on the planet compatible one, so that's easy enough. The actual stem though, that might be an issue. My parts are currently buried in a box somewhere so I can't get a measurement off of it to see what's compatible.
Lets check my usual parts supplier...
http://www.paintball-parts.com/16423...y-p/gp4682.htm
Bummer, sold out, and of course long since discontinued.
But they do list a phone number of a place that supposedly has a few in stock. Try and give them a call.