how to determine age on old kohler cast iron tub?

My grandfather has had an old cast iron tub for years and we were wondering how to determine its age. on the bottom it says:
KOHLER
64·5²·M·1
2 1

it's stamped:
D 8 22 17
92 87 198 (more but garbled)

thanks for looking

2 comments

Kohler

http://kohler.com/corp/about/contactus.html

by sweetpea on July 31, 2010 at 10:38 pm. #

have is appraised by an antique dealer.

by smokey on July 31, 2010 at 11:25 pm. #

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