Is there or is there not a Gibson serial number on the back of the headstock?
The bass was allegedly made by the former head of Gibson's former California CS, a man who would have access to Gibson components. And Gibson did send out components -- I've seen first hand evidence of it. Hamer never sent out components, and the the alleged time frame for this bass being made was many years after Jol Dantzig and Paul Hamer were doing work on Gibsons. So if there's a typical Gibson serial number stamping, I see no reason to think these are Hamer parts.
No stamp on the headstock, just the Custom Shop Decal (though I attribute little or no value to this as regards Gibson origin):
And, credit where credit's due, the seller pointed that out in the auction:
"The bass also features cream binding and beautiful bookmatched triple grade real flame maple top, a two piece mahagony body, mahagony neck with rosewood board, and is very light (approx 7.5lbs.).
The bass has a custom shop decal, but no serial number. Obtained from the original owner who had it built in the early nineties."
BTW, this thread
is interesting. Collective wisdom at work. Will Hamer now sue Gibson? How many more days before this thread is moved to the leper colony that is "Other Bass Brands" here?