The jukebox dimensions are: 60" High, 38" Wide, 26.5" Deep.
I think that would fit in the Sedan. What we can't tell is if the car is a two door or a four door and if it was a 6 or 8 cylinder.
The photo must have been taken in 1940 or early 41 as this jukebox was only produced in 1940 and 41 and as a Rock-Ola sales rep he wouldn't have been dragging an old model around. I also don't believe he would have cannibalised a brand-new car, so the suggestion that it could be a 1937 model seems to fit.
My wonder is how he coped with all that weight on the ass end. The jukebox weighs 410