We are looking at two sets of buildings: the main building that was constructed in the early 1970s as the headquarters for National Airmotive Corporation (now owned by Rolls-Royce) is at 7200 Earhart Road (but is associated with 7501 Earhart and APN 42-4404-11-2) and four test cells (1-4) (associated with the APN 42044-4-3 and 7900 Earhart Road). As I understand it, the test cells don't have a directly associated address.
The first owners of the first test cell (Test Cell 4)was Howell Propeller Services (Howell Engine Services) in 1952-1954, then Air Power Overhaul in 1954-1963, and then National Airmotive Corporation in 1967. I believe the other three test cells were constructed by NAC. Today there are two sets of test cells and we're looking at the southern set. Test Cells 1-4 with test cell 4 previously known as Building 602 and L-900, I believe.
It looks like I can't send a map, which I think would be quite helpful for you.