Even though it is basically the original YF-17 (ex USAF 72-1570), still the manufacturers wanted it to look like the F-18 prototype, which -- albeit of the same configuration -- was considerably heavier and with numerous other differences. This aircraft was transferred to the US Navy in early 1976, receiving out-of-sequence serial 201570 (one of many such serials), as seen in this photo. The Paris show number 42 can just be seen below the wing.