Hi all,
To shed some light on the subject, the numbers are Douglas “ship on contract” not the construction number. The B-17s built at Long Beach are easy they are all built on one contract and start at ship 1, 42-2964 C/N 7900 and end with last one 44-83885 C/N 32525. Note they are several blocks of C/Ns and serial numbers but the “ship on contract” are consecutive.
Here is another Long Beach built B-17 “ship on contract” 1155 from some movie I forgot the name of about an imagery worm name Curly. Ever note how many movies flight line scenes where shot at night in the Hollywood movies of the time, put the actors in B-2 bomber jackets it’s “somewhere in England” or Casablanca or wherever.

Where it’s gets to be a can-of-worms with Douglas is when different contracts are on the same production line like these A-20s at Santa Monica:

The ones on the left are A-20As for the Army, the ones on the left are Boston IIIs for the British with lower “ship on contract” number and a different series of C/Ns. Since the fuselages were built at El Segundo as were the A-20Bs built at Long Beach some references say “fuselage number”.
All the best to you all.
Tom