E-4C or VC-25B? E-4C is a Sierra Nevada contract and involves 5 airframes (747-8) and I believe they’re former Korean airliners…
Air Force’s New ‘Doomsday’ Plane Will Be Converted from Korean Air Passenger Jets
I screwed up my numbers. E-4 replacement is 5, VC-25 is 2. The one story I read on a defense website had the blurb about using a/c built for a Russian airline, but never left the factory. It wouldn't surprise me if Boeing found a cheaper source given it is taking a bath on those contracts.
Again, my bad on the quantity. Thank you for the correction.