Donald Farr
Former Editor, Mustang Monthly
June 1, 2009
Photos By: The Mustang Monthly Archives
Most Ownercards have been lost or discarded over the years. They are very important to numbers matching collector cars.

Documented original numbers matching: "This is the holy grail. Now you have a car that was born with these parts, restored exactly the way it came down the assembly line, and you have documentation to prove it. Probably the loosest form of documentation would be notarized previous owner affidavits - letters from previous owners that say this car, when they bought it, was a four-speed car. The next step up is dealer paperwork, like copies of the dealer invoices when the car was originally sold. The kicker is, all of this stuff can be forged; I have seen some brutal forgeries out there. Then you get into factory documentation - warranty cards and the original body buck tag. Of course, there are people who can make these things seem absolutely genuine, so there's this red-flag, buyer beware thing saying that just because somebody has this stuff doesn't mean it's original or authentic. The next thing is the build sheet. A genuine build sheet has all of the numbers and codes so it's the ultimate documentation."

Intact and readable build sheets are one of the most important documentations for a collectible Mustang. If you can match the codes on the build sheet to the codes on a car's individual components, you've found the holy grail.

Third party authentication: "This is the fourth leg of the stool. I call it the sprinkling of holy water. You now have people like Kevin Marti who can do the numbers analysis and tell you when a Mustang was built. You have the Shelby American Automobile Club to document Shelbys. I have a lot of respect for these third party verifiers. When you think about it, they have placed themselves in harms way to try to assist the hobby for a greater good."

Is Your Mustang "Numbers Matching?"
Stamped Numbers

  • VIN on data plate matches VIN stamped into inner fender and windshield tag ('68-'73)
  • Engine, transmission, rearend, color, and interior correct per VIN and codes on data plate
  • Buck tag (if equipped) VIN matches;option codes correct


  • Engine correct per block casting number and date code
  • Engine correct per VIN stamping (Hi-Po and '68 and later)
  • Correct engine tag
  • Heads correct per casting number
  • Intake manifold correct per casting number and date code
  • Distributor correct per casting number and date code

Kevin Marti's Ford database has made "Marti Reports" an essential link in the matching numbers chain.


  • Transmission correct per data plate code and casting number
  • Rearend correct for the vehicle


  • Correct tags on engine, transmission, and rearend
  • Correct tags on carburetor, steering box, radiator, etc.

Date codes

  • Dates on all components pre-date the build of the car by a few days to several months


  • Build sheet (should match VIN and equipment)
  • Owner/Warranty Card
  • Original sales invoice
  • Original bill of sale
  • Marti Report ('67-'73)