There is no confirmation for an exact model or year. There can be variations in things like fenders. Also, not all Schwinns matched the catalog originally, some being built up from parts or modified right at the dealer. A lot of the serial number information posted on the web is just plain wrong. Prewar is especially problematic as I understand it because no records exist. The best list I am aware of is this one, pieced together from known original bikes:
www.bicyclechronicles.com
I am not an expert, and you may get better information from others here. That said, here's what I see.
Your frame is definitely a DX because the middle bar has a curve in it. A postwar DX frame would have dropouts, tabs welded on for a chainguard, and a welded on tubular kickstand mount. Yours has none of that, so the "D" serial makes it 1939 or 1940. It can't be 1939 because 1939 DX frames were a one year only thing with a straight lower tube and tabs for a dropstand at the rear forks. Yours has neither so it is a 1940 DX.
You have a dog-leg crank. If you pull it out, it should have a 2-digit year forged into the center part. The digits might be reversed. I do not believe these cranks were used after the war.
The grips with an oval around "Schwinn" were available before the war. I am not sure about after. Others will know. Later on, one end of that oval becomes pointy.
The Excelsior badge, the sweetheart chainwheel, and the larger brake arm that says "New Departure Brake" with the 2 little lines below were all used both before and after the war.
Since it is restored, it is hard to tell if parts have been changed. Nice looking bike!