C34763 05/22 thru 05/29/1952. Number stamped on left drop out.
What's the tire size? 26 x 2.125? Are the rims marked S-2?????
By 1957 pretty much all the Schwinns had a model name on the guards and there were only two balloon bikes for 57, the Phantom and the Wasp. The 1" pitch chain was obsolete in 1957. If this bike is a 57, which I really doubt, it would be a middleweight. With the info and that one picture I'd say it's a 1952 D-12 even though it has a light that could have been very easily added.