Most dealers that installed them on new cars preferred American Sunroof Corp. sunroofs, or ASC as they were known. They have since re-named themselves American Specialty Car (to reflect their diversification of products over the years and new owners).
Mostly, they were moonroof's (glass instead of metal), which they invented and pioneered. If your's is glass, more than likely it's an ASC. You can easily identify it by looking at the top of the moonroof and you'll see the letter ASC silkscreened into the glass.
Good news is if you need parts you can still get them. As I recall they warehouse the old parts in Chicago. Get ahold of ASC and they'll probably point you in the right direction.
As far as the power supply goes it's probably tapped off the drivers side fuse panel as earlier stated. Usually if that hasn't come unplugged than it's probably the motor is burned out or the track is broken. Check the to see the spade connector hasn't broken off or is still plugged into the fuse panel then push the sunroof button, if you here motor noise but have no S/R movement, it's probably a broken track. If you get no motor noise, probably a bad motor. Either way it can be fixed.:icon_bigg