Karsten Solheim followed the 69 putter series with the B69, B68, B67, and B66 putters which he advertised as "Ballnamic Putters." [And The Putter Went...PING (2017) by Jeffery B. Ellis]. First offered in 1964, the B69-B66 putters were more heel-to-toe weighted than their 69 series cousins. Karsten filed for the patent on the B69-B66 designs in January 1965, and he received the patent on January 1966. 

This Phoenix PING B66 left handed putter is in excellent condition. PING moved from Scottsdale to Phoenix in mid-1966, so this putter dates from that time. Early left handed putters are difficult to find, as they were made in tiny quantities compared to their right handed counterparts.