My God, these manhour numbers thrown around are ridiculous.
In January of 1945, North American made some major changes to their tooling system as too many employees were standing around idle waiting for manufacturing tools and jigs. On a typical day, about 6,000 employees working 10 hours shifts each day were rolling out 10 Mustangs per day. After increasing the number of manufacturing tools and jigs and adding to the work force, 9,500 employees were pushing out 17 P-51s a day.
So, if you work the numbers, assembly times was initially 6,000 hours per P-51, decreasing to 5,588 manhours by July.
Yet, according to Lee Atwood, "The final 5,000 P-51 airplanes were built for 4/10ths of an hour per pound and sold for $17,000 each, less government furnished equipment: engine, armament, etc." So, the basic airframe, less engine, prop, guns, radios and various other components weighs about 5,580 lb. 5580 x .4 = 2,232 manhours. Installation and testing of equipment listed above must make up the balance of time. As you can guess, I have to do some speculation and make some assumptions.
Check out this
document Meanwhile, on Long Island...
According to the Grumman Historical Center:
In March of 1945, Grumman employed 17,731 people. Approximately 9,250 assembled F6Fs. That month (26 working days), these folks delivered 605 Hellcats. That's a average of 23.27 F6Fs every day. Grumman worked two 12 hour shifts. 9250 x 12 = 111,000 manhours / 23.27 = 4770 manhours per F6F. Both the numbers delivered and manhours per fighter were records for American fighter manufacturers during WWII.
My regards,
Widewing