That frame is one of the first batch of Monsters that had the monostay. That is the first version of the monostay that had the monotube pinched down to accept the seatstays which were just welded across the end of the monotube and then what was sticking out were welded together.
I didn't like the looks of that set-up and Chris didn't really like it either. Proper alignment was difficult also. The second generation design is much cleaner and looks like some thought actually went into it. It was also much easier to align and finish so it looked decent.
