20th Anniversary electronics are used in the 20th Anniversary basses and on custom orders only.
The control layout is very similar to a Series I - a volume, filter and Q switch for each pickup, plus a pickup selector switch. We also put a stereo/mono switch on the 20th Anniversary models. This has always been (and still is) an option for Series I and Series II, but it isn't standard.
If your bass is light then it's a Maple top, back and core with Purpleheart accent laminates. If it's dark, then you've got Walnut top, back and core with Vermilion accent laminates. Both styles had 5-piece Maple and Purpleheart necks.
Hope you enjoy that new-to-you bass.