its not a post card, its a cachet certified by the gateway stamp company, and they have been producing autographed cachets since 1977. they are postmarked on the date of the occasion they commerate. check the date of the postmark on the payton and see what records he broke and or set that day. their cachets are envelopes with silk screening on it and an official government postmark on it with a stamp. do you require any more certification than that? one more thing, every signature is witnessed by a employee of the company. thats better than topps, upper deck and playoff can say.
plus i have a payton signed lithograph produced by the walter payton foundation with the certificate of authenticity also signed by walter payton. 2 signatures for 1 piece, think about that.