One of the 2 chase planes supporting the first flight of the F-35B. Note the Lockheed Martin logo and the waiving Texan flag on the vertical stabilizer.
One of the chase planes during flight #20 of the F-35A Lightning II, was this F-16DJ. This plane is also used as a flying testbed for the F110-GE-132 engine, the engine used in the block 60 Desert Falcon.