I have never used Xpostfacto, so I am not sure. I just got that info straight off the Xpostfacto page. I was about to use it once on my PM 9600. It was using OS 9.1 and it was going to let me install it, but I didnt due to limitations, such as loss of serial ports so I wont be able to use Personal Laserwriter. Also the slow bus speed, which was stuck at 50mhz. And the internal floppy drive would not have been usable. I decided to stick with OS 9, and it did serve me well. Sadly, I no longer have my PM 9600, because I sold it for a good amount of money.