Why would you want to be running Flash Player 6 rather than Flash Player 7 on your system? Flash Player 7 isn't any slower (that I have ever noticed) than 6 on any of my 8.6 systems.
Hmmm...
And just in case this is because you saw something that said it requires Mac OS 9... 99% of everything that can run in Mac OS 9.x runs perfectly in Mac OS 8.6 (including most Carbon apps as long as you have upgraded the Carbon Lib on your system). I have Flash Player 7 installed on both my PowerBook 3400c and PowerMac 8600 (both running 8.6), and within Blue Box (based on 8.6) on my other 8600.
Hmmm...
And just in case this is because you saw something that said it requires Mac OS 9... 99% of everything that can run in Mac OS 9.x runs perfectly in Mac OS 8.6 (including most Carbon apps as long as you have upgraded the Carbon Lib on your system). I have Flash Player 7 installed on both my PowerBook 3400c and PowerMac 8600 (both running 8.6), and within Blue Box (based on 8.6) on my other 8600.