PT 8.0.4 to Mac OS 10.5.8-Won't Install

I get a "not compatible" message when trying to install a copy of PT 8.0.4 onto Mac OS 10.5.8. I read on another thread that 8.0.1 was the last compatible install but the compatibility grid shows 8.0.4 to be do-able. Any help or directions to a patch would be very welcome.