Steinway numbers

[Clyde Hollinger]

Friends,

I don't tune many Steinways.  Today I got my ninth, the first time I 
tuned a Steinway console (made in 1963).

Can someone explain to me the numbers stamped on the top of the 
pinblock/frame?  On the left side was the number 100, and under that was 
a six digit number, which I know is the serial number.  On the right was 
stamped "T 1762."

What is the "100" and what is the "T 1762"?  Thanks in advance.

Regards,
Clyde Hollinger, RPT
Lititz, PA, USA