The USAF ones belonged to defunct Russian airline Transaero that had ordered four 748 of which two were built but then the airline went out of business, the NTU were offered to PIA in place of a 77W order of five aircraft they had signed up for few years earlier, and later to Iran Air after sanctions were lifted briefly from the country, they had initially decided to take them but in the final order chose the 77X and 77W, In PIA case the aircraft was found unsuitable to operate from Lahore a major gateway in Pakistan, not sure how true this is.
Originally Posted by
procede
Was this one of the prototypes used for flight testing?
No that was the first A380 frame sold to Kingdom Holding in Saudi Arabia and was being converted into the first and only ABJ380, the Saudi firm decided to scrap the conversion and sold the aircraft.