Let's see if I can get this right. Essentially, the original Spyders were custom made for John Entwistle and featured, among other things, Series electronics. Subsequently, the basic body shape of John's basses was offered as an option and called the Exploiter body shape. Thus you could order any Alembic with the optional shape. That your bass has the S in the serial number and appears to have Spoiler electronics indicates that your bass is a Spoiler with the Exploiter body shape. Of the Exploiters dating from the '80's, it seems to me that the majority are Spoilers.
In 2003, Alembic started a limited run of basses which were actually called Spyders; see
here. These basses feature some special custom touches like web inlays and four part tail pieces.
From time to time, Mica runs serial number searches. Go to the Owning An Alembic section of the club and then click on Serial Number Requests. Post the serial number there, and when she gets a chance, and if she can find it, she'll post the build record for the bass. Hah! I see you've already done that!
