What is a 1940 chevrolet 15 passenger sedan it has a full floating rear axle orange clearance light on the roof. Looks lik someting a band would travel in.

 

Looks like a Chevrolet Deluxe of one manner or another. Probably a custom build like limo's, stretched out to accommodate the "Boxcar" racers of the day.

The hood is so long that it could likely have a Straight Eight motor under the cover. They were pretty much being phased out even before WW II occurred.