The plate looks clean. I gently ran a wire wheel for only a few seconds to get off whatever gunk the wire brush couldn't get and I can't find any numbers. Is also doesn't look like they were grind off either. Just looks like they were never there. Now this is a 1942 built January or '42 I don't know if that makes a difference? I haven't tried looking for those other numbers yet. Here's a photo
http://i1298.photobucket.com/albums/ag41/Steve_Pfost/photo19_zpse7714907.jpg


1942 BK 1/2 Ton Pickup
1954 3800 1 Ton Pickup