Friend just showed me a vintage p bass his dad bought. serial # 13943 (sounds like a 56), black with matching headstock. Any idea what this thing might go for, or if there is anything else I should check out about it? Seemed to feel really nice, not much wrong except a little wear at all. I figure you guys are better than any 'antique roadshow' so if you can give me a little advice, that would rock. Thanks.