Found a US JO bass in a local shop. It may be the best bass I have ever played. One small concern, it has no serial number that I can find. Also no model name on the headstock. Is this normal?
The necks on US Laklands are generally easily identified from the grain of the wood. The serial number would normally be on the side of the headstock - can't be removed without noticing. I don't know about replacement necks though. But, even on a replacement neck the "Made in the USA" stamp should be at the back of the headstock.

