E121-80 Mystery Back Revisited

[sreader3]

Here is my annual thread about my Joe Judge E121-80 with oddball back in case anyone has new information. The back is the same as Type 1 (as defined by Rhett Y.) except that:

1. It is reversed relative to Type 1;
2. The wording on the first line is smaller than Type 1;
3. The wording on the first line is center justified whereas the wording on the first line of Type 1 is full justified.

Although the card is machine-cut, since it is badly off-center I'm starting to think it may have been some sort of prototype or test print.

Has anyone seen another example of this "mystery" back, which I call Type 4?

Front and back scans provided below, along with a scan of a Type 1 back.

Any help appreciated. If none, I'll try again next year!

Thanks.

Scot