It has some strange/unique details like the hose mounts under the tt rather than top tube cable stops
and the welded on cable runners under the bb
Not sure if these things were added later or some form of Altitude customization as some '96 Explosif frames came with magura's
I think it must definitely be a Bizango, as the serial number format is right. I can't see the entire number but it looks as though it is quite low in the 1996 sequence, suggesting a 96 model rather than a 97. Normally you can tell the difference from the cable stops, but it looks as though none of the stops on this frame is original. I would assume that the original stops and guide loops were all replaced when it was repainted. You seem to still have the hole in the right hand brake boss though, through which the rear mech cable is supposed to run.