The builder's names were not recorded in 1976, and the employment records are not easily researched from that long ago. The wood card that you have will probably have more details than I have on the 3x5 index card.
HOWEVER
I don't see the index card or file for your bass. So it's either 1) lost, 2)pulled awaiting to reply to a previous request 3) misfiled.
I would appreciate if you could mail me a copy or photograph of the wood card, along with your current contact details, and I'll make a replacement file with this information. If the original card/file turns up, we'll combine the information.
Thanks for the help, Jimmy! He knows first hand as we recently dug through some really packed files together. BTW, the numbering isn't reset, but there were a few ideas early on with several tracks of numbers (A, AE, AC and no letter were all made at the same time). Later, these tracks were all fused into the main sequence of numbers.