The Vehicle could of been in an accident and the drive train pulled and the body sent to the wreckers. It could of sat in the wreckers for years and years and bought later in life and is now back on the road. Just read about the A12 1969 Super Bee Mod Top that was dragged out of the southern USA Auto Wreckers and up to Canada and then sold back into the USA. I sold an A12 Road Runner to a friend 30 years ago body only and he was contacted last year by a person that had the original motor to the A12. Things happen for the good sometimes with information on the internet.
BS23H1B345752 could be the vehicle the motor was from.