Boiler Age Needed Please

I have an American boiler (which I believe was part of the company that later became American Standard) Boiler #4GA-8E Series #8B-J13

No serial # or Stamp???

Any help would be appreciated!!!

WAG from the 1950’s. Have a look at: http://www.heatinghelp.com/library.cfm#American%20Standard%20Heating%20Products