The sidehack resembles Indian side cars from the 40s, but I could be wrong. Great photo by the way..
Most 20s and 30 hacks had a different look.
It does lack the seam on the Indian hack but us similar.
Frank, the Militor came from the factory with that sidecar rig. Militor went out of business in 1922 and this was one of their final models. I have included a couple of photos of the bikes. The color photo is one that I took at the Springfield Museum in Mass., also home of the Indian museum. Militor was made in Springfield, very near to the Indian factory. Maybe they shared the same sidecar parts?
The B&W photo shows the bike and sidecar as it came from the Militor factory.
My dad was born in 1933, the photo of my grandfather was taken at that time or earlier so it's definitely not a 1940's rig.