Dating ACO Silos

Have you ever wondered how old your ACO silo is?  This could be a tricky proposition without original work orders or receipts.  However, I have seen two different ways that the original workmen left clues for dating when ACO silos were constructed.  The first, Picture 1, shows an ACO silo with the date “1941” written in faint white paint near the inside top of the silo.  The second, Picture 2, shows the date “1919” stamped in the periods between the ACO letters.  If you discover another way to tell, feel free to contact me, I am always looking to learn new things!