www.klov.com  If the game that wa in it is jamma, the cabinet is jamma 

  Joust was not.  But if this was a conversion cabinet that doesn;t mean the cabinet isn;t jamma.  Some coverter could have taken place.
BTW, if it is or isn;t jamma, like I said, it can be converted easily.  JAMMA is just a wiring standard.  It's that harness that plugs into the game.  Standard pinout.  Old games won;t be JAMMA but can easily be converted since it's the same hardware, just wires need to be wired to the jamma edge connector.