Contrary to what is stated in Formerly-Used Defense Site (FUDS) report # J09NV0985 (1991), this former gap-filler radar annex is still extant. It is located right alongside State Route 400 a few miles north of Unionville.
 
  
This photo shows the Unionville GFA immediately to the west of SR 400.  The building appears to be privately owned now.  [looking south]  
 

 
This photo shows the former GFA building and the three radar-tower foundations to its left (south).  SR 400 is in the foreground.  [looking northwest]  

This photo shows the rear of the building.  The radar-equipment section is on the right, and the diesel-generator wing is on the left (west).  The three radar-tower foundations are visible to the far right (south).  [looking northeast]  
 

 
This photo shows the gap-filler building and the three radar-tower foundations / footings.  [looking north-northeast]  
 

 
This photo shows the east and north side of the former GFA building; the diesel-generator wing extends to the right (west).  [looking southwest]  
 

This final photo shows the north side of the former GFA building; the diesel-generator wing extends to the right (west).  [looking southeast]