I would be very suspicious of any quoted manhour figures.
There are fabrication hours, there are subcontract fab hours, component assembly hours (in house/outsource) and final assembly hours. It gets even more complicated when some functions are are carried out in different factories. And where do you measure, at which point on the learning curve are you talking about?
The net result: unless a very careful, objective, comprehensive comparative study is undertaken by a knowledgeable person or organisation, with unfettered access to all the records, I would assume any quoted manhours to be purely speculative or, at best, slightly educated guesses.
oh, yes, I forgot... and, believe it or not, there are many reasons in many organizations to not tell the truth!