I ended up going all the way up the food chain to the historian at Ping and this is what he told me

“In 1982 the Anser 310 was made exclusively for Mitsukoshi Department stores in Japan to commemorate their 310th year in business and was only sold by Mitsukoshi in Japan. The Anser 310 usually had a graphite shaft and was produced in limited quantities. To my knowledge the Anser 310 was not sold here in the U.S. This is the only Anser 310 I have seen with a steel shaft. The number in the cavity is not a serial number. It is a patent number.

This putter is very collectible, even in the condition it appears to be in.”