Which is how I changed the end connector over to a molex, even with the above it fried the old 20MB XT (no great loss there).
i'm not sure if I understand. you need power for HDD, not a590?
just use the multimeter to check the pinout. iirc, two in the middle are probably GND. so you're chances are 50% anyway..
perhaps those very old hdd use different pinout? (I know that is the case with 3" floppy drives, for eg.)
