Navaleye,
I believe Ward mentions that he got one over 40,000 ft on the trip to the South Atlantic.
On a lighter note, (for once), when on exchange myself and one of the other 2 USMC officers had an informal competition about the attainable altitude in a Night Attack AV-8B with the 408 engine (same as the big motor in the GR7). He won by 200 feet.
I have HUD video showing 51,220 feet.
P.S. Please, don't any of you spotters out there tell me about the height limits on the OBOGS and pressurisation. There's a little bit of Farley in all of us.