^^ Exactly & other attributes^^
One Tact I take is, Naturally a Seller will not or cannot guarantee authenticity (In Many or most cases) for Such a rare and desirable item (Like WIlliams Buyer-Beware), WHY would they NOT send the Unit to a known rebuilder with the ability to also authenticate - cert the part at such a low-cost outlay to its possible value in the market, & If I encounter reluctance or reticents to this it often explains the sellers lack of faith in the very part they are offering.