David - If the bass were a 1974, the serial number would be in the 64 range. BUT, by serial number 64 the batteries were moved to the back of the instrument and not under the front plate of the bass. This bass could be older, or not. They were experimenting back then. If the bass were a 1974, then the pickups were definately changed. The pickups used back then only had one screw hole per side and not two. Also the Alembic embossing did not show up on the pickups until MUCH later. But I guess without a clear serial number, than it would be hard to tell what this bass started life as. With a good serial number Mica can usually tell all. As far as the XLR is concerned, that cannot plug directly into a mixing board. The XLR connector on that bass should be a 5-pin and not a 3-pin connector. The 5-pin connector is used with an external power supply. The power supply of course supplies power to the on board electronics and splits the signal for stereo operation. Is there any way you can get pictures of the inside of the instrument? From what you are describing, the bass may not have series electronics at all. If the positions on the toggle switches are only 2 way, you may have a bass that was fitted with signature electronics. Without holding that bass in my hands, that is about as far as I can go. Anyone else?
Michael