What is the age of my Grandmother Clock 1191

by Eydee Marie
(Edgewood, NM , Usa)

Hi, I am trying to determine the age of the clock inherited from my Aunt, who hd inherited from her Aunt.

I have some paperwork showing it was overhauled back in 1964 and then many years later when she actually received it.
The numbers on the back right hand side are in black block 1191
It has a metal/brass mfg label Colonial Mfg of Zeeland Michigan.
I Am unable to post a picture at this time. (I pad not cooperating,)
Any info would be wonderful,
Thanks!
BTW, the clock is ticking right along and is in great shape for the many?.? Years it is old!