There should be 4 pins, 3 being together then a empty space and then the last pin. The single pin is common ground for all leds, the first 3 pins are signal. The middle signal pin is floppy but I can't remember if HDD is the first or if power is. For the A1200T project I'm working on I made a little print board with a cable going to the motherboard and pins for the cables from the tower to go on.
