Beg to differ with you Guy, but that is N4A (out of a few that were registered as N4A, although not at same time)
You are correct that it is no longer in the current fleet.
Photo ID: AC73689
http://www.airport-data.com/aircraft/photo/000073689.html
It was replaced by a 'new' N4A registered GZ-20 of which you have two photos posted under N4A.
The GZ-22 (N4A) c/n 4120, named "Spirit of Akron", was retired after deflating in November 1999. (post crash October 28th). It was designed by Goodyear and built by Loral Corp as a proof-of-concept for military.
It was turbine powered.
The N4A registration markings are visible on the engine mount/cowling(s)..
Regards
John