There's a lot of cars that 'live on' with a transplanted vin plate. See: barn find Hemi Cudas. And that's about all you can use from that last car.
Carroll Shelby was not adversed to switching the ID's on cars. Hence, the controversy as to when GT40 P/1031 became P/1047.
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"LeMans, June 10/11th, 1967 was the next event for this car. This is the race where it's unclear as to which serial number (#1031 or #1047) this car actually carried. Documents show that the car was now light blue with roundel #57 and was entered by S/A with the driving team of Paul Hawkins and Ronnie Bucknum. Records also show that #57 qualified 5th with a lap time of 3 minutes 25.8 seconds, and quickly jumped into the lead once the race started. After numerous routine (and not so routine) pit stops, #57 was in ninth overall position when after 17+ hours it finally retired with a seized engine, on lap 254. Incidentally, the gold #5 MKII (the original #1047), crashed/DNF'd 5 hours earlier and would never race again in 1967.
Less than 2 weeks after LeMans, Ford of France entered this light blue MKII car (originally #1031 but now officially known as #1047) in the Rheims 12 Hour race, June 25/26th, 1967. Carrying roundel #1, it was driven by Jo Schlesser and Guy Ligier. They qualified in 4th place. After the traditional Rheims midnight start, the car ran strongly throughout the race. It crossed the finish line at noon the following day in first place, recording what would be the final win for a MKII and the only win for a MKIIB! Photos of this car at Reims show a small brass FoMoCo ID plate on the bulkhead, a plate that it still has today... stamped #1047
One fact remains clear though: after 1967 LeMans this light blue MKII (originally #1031) was identified on paper, on its FoMoCo ID plate, and on the race track, as #1047. This is substantiated by 1967 Ford documents. They prove that, post 1967 LeMans, this light blue #57 MKII (originally built & raced as #1031) was legally re-assigned serial #1047 by Ford & Shelby American, and that ownership was transferred to Ford France. Ford France continued to race the car (as serial #1047) in several more events in 1967, resulting in an important footnote in the annals of Ford GT history: The last MKII (and the only MKIIB) to win a race."
http://www.racingicons.com/gt/1031_1047.htm