1. Packard used a diagonal script on the left hand side of the rear deck that said "Packard" -- this photo and your photo indicate the diagonal script.
2. The rear window shape is the same in both photos and the curvature of the trunk lid appear to be the same.
3. The bumper appears to be the same in both photos.
4. While a number of makes and models used rectangular taillights on the lower edges, both of these photos indicate similar shaped tail lights.
5. The trunk handle on the 46 Package hung straight down and was a very heavy fixture like on the mystery car.
But I could be wrong. My first guess was a Hudson, Nash, or Olds but checking photos on Google lead me eventually to the Packard.