An odd question about top vent tabs

[crowderjd]

Hey all, does anyone know for sure when the top vent tabs went from square to rounded?  Do only Wood Dales have the square tabs on the top vent?  @Craig?  @harris92? 

[harris92]

Somewhere between late 1963 and early 1964.  Some of the early Arlington Heights lid vents have square tabs.  Craig has a chestnut with this feature.

[crowderjd]

Thank you!  I may make a purchase then