I have been seeing a few basses around on the internet that look just like an SB-1000 (same pickup and electronics setup, bridge, neck thru, finish styles etc) EXCEPT they have almost a fender-style headstock, its 4 on a side instead of 2x2. What could it be? The pics of the headstocks are always too blurry to read whats written on the headstock other than Aria Pro II.
That would be the RSB-900. RSB meant "Rev-Sound Bass". There was also RSB-800 (two pickups, passive) and RSB-600 (one pickup, passive). Here is a catalog shot and a headstock closeup.

