Been trying to find out what the id numbers mean, 51SL66923M, the other number is BU58B-80-676-29M-630, If anyone tell what they mean, I would be very happy, Thanks John
The VIN you listed is not correct for a '56 Mercury. Should start with 56 and not 51. The SL stands for St. Louis assembly plant. The other numbers I'm not sure of except for the body code (58B) which means Monterey Sport Sedan (4 dr.). The other numbers are body paint color, interior trim and Mfg. date (I think is 29M, which I'll take a guess is the 29th day of December, '55 ?).
Mid to late 50's Fords generally had the VIN number stamped on top of the passenger side frame rail somewhere between the firewall and grill, or on a front cross-member. There were different positions depending on the vehicle year & model: truck, full sized car, T-Bird....
The Mercury's may or may not be similar.