The first one like you're describing came out in '39 in chrome for the deluxe bikes. It's called a bird wing. Then offered on DX bikes in '41...painted only, no more chrome. After the war, the birdwing became the feather and the mounting changed to the modern type with lugs on the frame.
The boys and girls DX had them, the Cycle Truck and Hornet had them, and I imagine a few others I can't remember. Cycle Truck and Hornet guard had a flat area for the decal. The DX was plain and no decal, other than the round Schwinn cross. Gary