Hold on to your hat, Brian ... EUREKA! I just added a puzzle piece!
The attached online photo shows another model that was a 50th Anniversary model (805-B or 805-BA)! Photo 2 is a corresponding preview that verifies it. So there were actually three golden anniversary models!
Keep a lookout for photos of the model-types 805-B (shipped Apr 1958-Jul 1959) and 805-BA (shipped Aug 1959-Mar 1960), which are both likely pastel green and iridescent cream. Would both have been tagged with anniversary decals, or was the attached preview missing the 'A'?
Another thought I had ... the 960-A might also have a Golden Crown! So be alert! Maybe the 'A' (missing in the preview) simply indicated that it came with a Vibra-Beat nozzle?
Btw, I searched and searched but found no mention of a Eureka 25th anniversary model vacuum cleaner (I checked both 1934 and 1935).
So which of us is going to locate photos of the models mentioned in this message first? 
Or will it be someone else?
The pièce de résistance is that they likely are all enameled in St. Patrick's Day colors!
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