Hi Deb, and Welcome. Sorry to hear about this. Your boyfriend had a Classic Alembic, for certain.
Yes, it will run on two 9v batteries but it will consume them quickly, and unless the 1/4" jack is wired for mono output, you will only hear the neck pickup without a special adapter cable. They are readily available, but not inexpensive. You're better off since you have it, to use the DS-5 power supply.
That said, the batteries go in the square box located in the center of the neck beam, on the back of your bass. (Here's the reverse of my '77...)
Please post us some pictures when you can.
*and tell me about "banjo"... I build, and work on them!
