It's a bit of a long story. Both airframes came out of the Israeli AF, of which all of the IAF Mustangs had their identies swapped and paperwork mixed while in the Israeli AF, all essentially in an effort to erase the previous traceable histories of the aircraft. There was no identity with the airframe that TFC owned, other than a Swedish data plate mounted on the tail, which the serial number, through paper work, tied it to being 44-63864. When this was established, the belief was therefore that the aircraft was the actual wartime "Twilight Tear". A strange oddity was found, however, when the aircraft was stripped of paint to be painted in the markings of 'Tear'. The name Lt. Bert Lee was found scribed into the original metal, just below the canopy of the aircraft, on the left side, and near to it were two Japanese flag "kill-markings" also scribed into the metal. This was cause for some question and curiosity, but the plans went forth and the aircraft was promoted as the original "Twilight Tear", as that was the best they knew about it. However, some real questions began to be asked shortly there after, as the wreckage of a former IAF Mustang, that had crashed en-route to the U.S. in 1963, had been recovered and was under restoration. The identity on this one, through a good number of sources of evidence found in the aircraft wreckage, was 44-63864, and this simply couldn't be argued. By 2007, even before the TFC machine came to the U.S. for the GML event, there was an effort to find out who Lt. Bert Lee was, and find out the true identity of the airframe. Lt. Bert Lee was tracked down, and although he had passed away, his family was contacted. A photo of the Mustang that Bert Lee flew in the Pacific, clearly showed the exact same name and kill markings scribed into the metal, just as could be seen, clear as day, on the TFC Mustang. It was also found, that while the aircraft was used by another pilot, later on, the aircraft was given the name "Fragile But Agile". In 2007, when the aircraft came over for the GML event, it went to Fighter Rebuilders immediately after, for a full restoration. At the time, it was said that it was being restored for The Fighter Collection, but as it was sold soon after the restoration was initiated, I think the plan all along was to provide the best opportunity to correct the identity of the aircraft, which couldn't come at a better time than during the process of rebuilding it. Both parties ended up having to prove the identities for each airframe, to both be registered under the FAA, with the now known true 44-63864 being registered as such, and the former TFC machine provided the serial number 44-12016, believed to be correct to it. By late 2010, the restoration of the former TFC machine was complete in its new identity, believed to be its original, as "Fragile But Agile" (a combination of the markings that were on it when Bert Lee flew it, as well as a later pilot), a P-51K, so it is also configured now as a P-51K, with the proper prop blades and nose cone (the only one of its kind). It is based in Texas, as part of the large flying warbird collection owned by Tom and Dan Friedkin. 44-63864, the actual original "Twilight Tear", owned by Ron Fagen here in Minnesota, completed restoration early last year, and that is the one I have depicted for this product.
As I've mentioned before, there is an interesting detail that supports all of this even further, that hasn't ever been talked about. The original "Fragile But Agile" was a P-51K-10-NT, which is quite an early variant, and had fabric elevators. The former TFC Mustang, now restored as "Fragile But Agile", as it is believed to have originally been, had farbric elevators all the up until its recent restoration. The original "Twilight Tear" was a P-51D-20-NA, that had metal elevators, and that was what the wrecked example from Iceland, proven to be the original "TT", had.