Original head light lenses have this number cast in them.
Check out the cad plated plug for the speedo reset button. in 1938 HD started using a magnetic speedo lock for police bikes. This required putting a 3/8 hole in the left side of the dash. If the bike was for police duty, it would have a little spring mounted reset knob riveted to the dash base and the hole in the dash would be left open. If the bike was or is a civilian bike, it gets this little plug installed. There are two little tabs on it that get bent over and hold it to the dash.
The dash fits amazingly well on the up side. I love the cad plating and parkerizing next to the blue paint. Check out the short knurl gas cap, this was the style of cap that came out in 36- sometime in 41, hd started getting caps with longer knurls on them.