Case closed-
I finally found one on ebay. It looked great, but the description was worded such that I thought it might be a reproduction of some sort.
"brand new factory cut"
"plastic translite sheet"
I think it's new old stock. It had a label to a vending company and an invoice inclosed from 1981.
I thought it might be a shame to install this, but shoot- it's going to replace the crappy one on my game TONIGHT!
K