That's probably a sequence number on an assembly line. Early Corvettes had a similar number stenciled on one of the frame rails, which just happened to be upside down due to the position of the frame during the early stages of chassis assembly. A "numbers-correct" restored 59 Vette that I inspected for a potential purchaser from France had that number in the correct position and orientation according to the original build sheet. The car had a total of 9 miles on it since a frame-off restoration job when I test drove it. The purchaser paid $90K for it, plus shipping to France!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!