Looks like a SB-1000 to me too. I have owned one over 30 years, great bass. They do have issues with the pickup though.
Here is some info I collected. http://www.matsumoku.org/models/aria...ass/sb/sb.html
Note: SB = "Super Bass" for those who are interested.
Manufactured by: Matsumoku, Japan
Year of Munfacture: c1980/1
Body: Super-balanced Canadian Ash
Neck: 5 ply Maple/Walnut Transmit (Thru-) type with Heeless Cutaway. Aria's catalogue states: "Contoured as a Heel-less on the back of the transmit neck of the SB series. This Heel-less cutaway allows easy fingering up to the 24th fret."
Fingerboard: Jacaranda Ebony
Fret Inlays: Mother of Pearl (Flush)
Fret Qty.: 24
Bridge-tailpiece: Brass. Aria's catalogue states: "Sturdy manufactured die-cast bridge. Our Quick-Hook system provides quick string replacement."
Machine-heads: Die-cast (Schaller Type)
Pickup: MB-1E Double-Coil with Active Noise Killer Circuitry
Coil-tap (BB circuit bypass) Switch
6-position Rotary Attack Mode Selector (Mellow -> Bright) with dot position marker
LED Battery Indicator
Recessed Output Jack