I like aviation history and, like many others, enjoy the tales of oddities, one-offs, and planes that never quite made it..
My dad had a hand in one such bit of history. The P-51 (later F-51) was the dominant U.S. land-based fighter of World War II: indeed, it stayed in service into the 1980s, and the Dominican Republic have retired the last operational Mustangs in 1984. Not bad for a plane built in a tremendous hurry and rushed into production: the most famous model, the P-51D, could escort bombers to Berlin and was vital to the US air offensive. (It also starred in the well-meaning but historically and technically screwed-up movie Red Tails).
Anyway, when my father was working for Piper Aircraft in the early 70s, Piper developed a ground support plane for a USAF competition (PAVE COIN) for a cheap export aircraft (the USAF was doing a separate program for its own needs, which led to the superb A-10 "Warthog"). Dad worked on it at Piper in Vero Beach, FL, where we lived, and I remember him going to the "fly-off" at Eglin AFB to support it in competition. The PA-48 Piper Enforcers were heavily modified P-51 airframes, armored and fitted with Lycoming turboprop engines. Alas, they never caught on with the USAF or anyone else, and one was destroyed in a crash into the sea off Vero Beach. Dad had a lot of fun on that project (and worked a ton of overtime).
Dad told me that, even with the addition of more weight including wingtip tanks and underwing stores pylons, the Lycoming gave it so much power the Enforcer consistently outran the P-51 being used as chase plane, and Piper had to rent a T-33 jet to do the task instead. One pilot told him the tests were being monitored by, of all people, British intelligence, one member of which said they found it odd Piper didn't scramble its radio messages. This program was a departure for Piper anyway, since the company had never built an armed aircraft and hasn't since. Florida's representatives continued to push for it, even claiming it was better than the A-10. (I have a memory for these things, and I read a mid-70s headline in the paper that said, "Air Force Overlooks Enforcer; Better, Cheaper Plane.") The program did have a sort of coda, with two new planes built by Congressional direction in the early 1980s, though Dad had left Piper at that point and was not involved.
According to the Aviastar website, the surviving plane Dad worked on (known as PE-1) is in storage somewhere. He hopes it joins the 1980s airframe that's currently on display in the Air Force Museum in Dayton, OH. If the plane is ever properly displayed, Dad hopes someone opens it up and looks at the job he did wiring it. Not only is the wiring precise, it's completely clean, not a drop of solder out of place. He hopes someone says, "The SOB who wired this thing knew what he was doing."