Before you hop on me about how the numbering works. I know the first and smaller number is the year for the contract the aircraft was bought under. Or something to that effect.
However, I was wandering around the USAF Museum (The new, silly name escapes me). While staring at the F-4 of Col. Olds, I noticed the Tail number started with 40. Was the F-4 Phatom our secret weapon of WWII or was a different numbering convention used whenever this particular F-4 was ordered?
The offending number:
In case anyone forgets what an F-4 looks like