It is a checker 1946 rear engined prototype named Model B.
The objetives when this prototype was developed, as Herb Snow outlined in the a 1945 memo were: " The primary purpose of a vehicle of this kind is to carry passengers confortably and economically. To do this, passengers must be placed in the most advantageous seating and riding position. The vehicle must be light in weight if it is to operate economically. Keeping weight to a minimum means that entire vehicle must be as compacta as posible without any sacrifice in passenger space". This led Checker to this rear enguined design that left the whole center of the cahssis free for two full-width, face to face passenger seats. The prototype used a side-valve Continental six placed transeversely just back the rear axle. The body of this proto was povisional. (Special Interest Autos Aug-Oct 1973) After extensive testing of two prototypes, the configuration was nixed due to its inherent instability during cornering caused by its rear weight bias.
I hope this was enough for the point. Thanks and greetings.
