Is there a version of PD for Mac OS9?
If there is, where can i find it.

best regards,
Per

I am pretty certain the answer to this is - No. Max MSP is the only equivalent that works on that OS. If you are looking to use free software I would suggest using older versions (2.something) of Supercollider. It should be noted though that Supercollider does not have visual processing power of the likes of GEM.
Hope that helps