You have a very early Series I. If you absitively, posolutely gotta gotta have a model name, it is a Series I LSB (for long scale bass) but nobody really uses the LSB & SSB designations anymore. Lack of a truss rod cover makes me think it is mid to late '70s. I had a '74 without a truss rod cover and a '79 that did have a truss rod cover. All of the ones I've owned since ('83-'00) have had truss rod covers.
The serial number is either stamped into the wood on the 24th fret (that's where it was on my '79), on the top edge of the headstock (my '74) or inside the control cavity. Sometime after my '79 was made they started stamping the serial number on the truss rod cover.
Contact Alembic through their website Alembic.com, or through the Alembic Club that you can also access from the website, and they can look up the build history for you.
Do you have the external power supply and 5-pin cable? If not, then you have not yet fully unleashed the beast that's sitting on your guitar stand.