Thank you Z118.
With this info in mind I took another look. It appears I missed the numbers to the left and right of the I/O maker mark. There is a seven to the right and left. I must have thought it was part of the design and not an indicator.
So this tells me it was made at Plant# 7 , year 7 of production in 1936 (an assumption), mold detail #5 ( as in 5 gallon. Another assumption)
It is still a cool bottle. My wife would like for me to make a wooden stand so that it sits on a vertical and to place plants in. I can do that.