There are 6 variations of the 1974 glass, although many people only recognize 4 of them.
When the 1974 glass was first made, the 1971 winner's name was listed as Canonero which is an error. Some 450,000+ were made this way and when the error was discovered, they redid the entire run of 450,000+ with the correct name of Canonero II. Since there are about the same number of correct vs. error glasses out there, there is no added value to either.
Because of the way glasses are marked on the bottom by the manufacturer by simply enbossing the mark in the glass while it is still molten, many times the mark will fill back in resulting in an unmarked glass or one with a partial mark that is indistinguishable. Many consider these to be the same as a Libby glass, but some exacting collectors consider them another variation to have to collect. These glasses are valued the same as a Libby glass.
Here are the marks you will find embossed in the bottoms of the glasses. They don't show up very well in photos so I also drew over them to give a better idea of what they look like.
For current pricing info, check the Equillector site, but generally speaking the Libby/unmarked glasses have a $5-$10 value while Federal glasses are gradually climbing and are easily $150 each now.
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