Actually, it probably IS a J-Custom. Most likely either an S3040PL or BS, or perhaps an S540-Japan. There were actually 6 or so different J-Custom S models.
What is the finish like?
If it's a strange kind of oil-looking multi-color, it'd be an S540-JAPAN
If it's a pearlescent white or a trans. brown sunburst, it'd be an S3040.
Those are the most common.
