I believe your blade is an aluminum Hamilton Standard blade that has been machined to fit into a two blade, ground adjustable split hub commonly used in orchard fans. That explains the funky shaping at the root and why there are no blade numbers. Attached is a pic of the butt end of an original Hamilton Standard prop blade and an example of the spit hub. Notice pins at 3 and 9 o'clock, screws at 12 and 6 o'clock. Looks like your blade has pins and screws in the same orientation and the remnant of the bronze insert. Without the drawing number, you'll have to get contours off an original B-17 or B-24 blade to try to match it up, but the installed diameter of your 66 inch blade is in the right ballpark. The B-17 prop diameter is 11 feet 7 inches.