So according to the customer service rep at Ibanez I corresponded with, this bass is a BTB600ENTF, made in 2003; and they said the “bartolini customs” are original to the bass. That model number pulls up absolutely no google results, and the rep said this was quite an obscure BTB, and they didn’t have any literature on it in their possession. Why this thing is so obscure is essentially speculation, but the mismatched hardware makes me think this may have been a production sample kinda thing for a more premium j/j option to the BTB300. I’ll be sure to update if they have any more info for me.