18.5" kettle score! How old is it?

How do you know how old a weber kettle is? I scored an 18.5" kettle with wooden handles, and 3 - 2 on the bottom of the kettle and one on the lid, and 3 daisywheel vents on the bottom of the kettle and one daisy wheel on the lid.

I'll try to get some pics sometime soon. I got the kettle and a bunch of coleman gas lanterns when cleaning out a friends family barn. this was all getting tossed out!!! :crazy:

looks like the 18.5 is an '81 model and a 22.5" kettle I scored a few months back is from '83. Nice!

Now is deciding what to do with them!! lol. Thanks!!