hi sergio
welcome to the club!
it's a fascinating instrument, very beautiful. it seems to me that your bass has several interesting features. first of all, it's a 'series' instrument, which means that it has single-coil pickups with a dummy humbucker (the black rectangle between the pickups) and special electronics, designed by alembic founder ron wickersham, that make make them work together. series electronics have been discussed at great length and in great detail by many contributors who are far better-informed than i am; just do a search and you will have a library of information to read
the peghead is unique to my eyes, and indeed all of the woodworking is pretty special. i've not seen a 'hippie sandwich' (that's alembic-speak for the sequence of ten wood laminates) quite like yours: it's asymmetric, which is unusual in itself (though not unprecedented), and woods are striking. the neck laminates are also very cool
the body shape, especially the slender horns and the shallow omega-cut, is also a bit different from anything i've seen. the brass backplates look much newer than the rest of the instrument, but that's just a guess
is there a serial number on the instrument itself, in addition to the s/n on the preamp? alembic keeps an information file on every instrument they've ever built; if you can find the serial number, mica can tell you when it was built, what woods were used, and many other interesting details. also, there are many experienced members who probably can provide more detailed information about your bass
congratulations! you have a beautiful vintage alembic
marc