I've received an answer from Winning Moves in regards to my question:
Winning Moves wrote:
It is based on the 1975 version but also pulls in some of the more popular features from later editions. In short, it most resembles the 1975 version and NOT the most recent ones from Hasbro in the late 90's.
I do see in the Winning Moves instructions for their 30th anniversary edition that they do have junk mail. It appears their version is a hybrid between the original and later versions, with an emphasis on the original.