I still have many 720k drives around, some HP gear
uses them :)
FWIW, I've had no problems aligning the Sony 3.5" drives used in older HP
stuff with a normal alignment disk.
I really must work out what the alignment tool really was. It's like a
screwdriuver with a pinion and spigot at the business end. The spigot
locates in a hole in the drive chassis, the pinion meshes with teeth on
the stepper motor flange and it makes moveing the motor a lot easier. I
need to work out the number of teeth and the pitch, and I'll have a go at
milling one.
-tony