Glenn:
Sorry to hear you have to sell such a lovely guitar. I believe Alembic was making only Series instruments back in '76. I have 76-476, a medium scale Series I guitar. A Series will have two single coil pickups with a dummy hum canceling pickup in the middle. It will also have a 5 pin jack to go along with the standard 1/4 phono jack. As for value, it depends on condition, any extras (like LEDs or extra special woods), and whether it has the power supply. If in good condition, it could be worth anywhere from $2500-3500, perhaps more for a special top.
Bill, the guitar one