I have a left and a right Bear Polar, and am just hoping to confirm the year. The catalog disk that I have says '61 was a 66" bow, but the left hand bow in the pics below is 64". I found a thread where Jeremy confirmed that there were 64" Polars made that year, so will take his word on that part of it.
Was there a difference in glass colors that year as well? The first picture below shows both bows side by side. The LH bow has white colored glass, but the RH bow is a light green. The green color doesn't show very well in the pictures - it is actually almost a light lime green.
Still, 1961 is the closest thing I could find on the Bear catalog CD.
Both bows side by side
Right Hand Bow
Left Hand Bow