Pre 1970

[ChuckO]

Does not appear that it's stamped with a Pat-pending, so I'm guessing this is a 1964-69 BBQ. It doesn't have the original ash-catcher, but the kettle appears to be in great shape daisy wheels on the sides and all

http://sfbay.craigslist.org/sby/for/5254344501.html

 

[Nate Frost]

It's most likely an early 80s model, probably 1981. It looks to have the 2 rivet lid handle. It also has wood bowl handles.

 

[Clark "Harbormaster" Hodgson]

It's most likely an early 80s model. It has wood bowl handles.

Yep. It also has the raised Weber lettering on the vent, it has single screw wood handles that were introduced in the early 80's, the wheels are not 60's or early 70's vintage, and it has the One-Touch cleaning system.
I can almost guarantee there is a date code on that exhaust vent.