That may have been an AWSA three event sticker, I've seen a couple versions. I have one on the back of my Nautique.
That might be the one, could you take a picture of it and send it to me if possible, if I see it I will remember if it is the same one, thanks, Rodney S.C. ( rodneyyon@comcast.net )
If you can make a copy of the invoice that would be great. Black out your name if you want but I think an original invoice would be a cool addition to the the site. Daniel