Before the big boxy taxi, Checker made the Model A, here is a photo with a 1940 example

Via Shorpy. There are two in the photo, click on it for the full size, one is right behind the unbrella holder. Notice the antique 2 bulb stop light as well.

Hot Rod Checker Marathon Taxi... that is cool!

For more on this Checker, see Tere's photo gallery: http://justacargal.blogspot.com/2009/04/good-guys-reflections-omg-marathon.html