 Number matching

Number matching or matching numbers is a term often used in the collector car industry to describe cars with original major components, or major components that match one another.
Many times these major components contain dates, casting numbers, model numbers, Vehicle Identification Numbers (VIN), stamped numbers, or codes that can match the original components that were on the car when it was new.^{[1]}^{[2]}
Contents
Definition
The term "number matching" (or "matching numbers") is a term used in the collector car industry to describe the authenticity of collectible or investment quality cars. Number matching generally means that a particular car still contains its original major components or has major components that match exactly the major components the car had when it was new. These "major components" are not always agreed on.^{[3]} The appearance of a number matching car likely could not distinguished from an original car. A site by the name numbermatching.com (direct link removed since Firefox reports this site as "suspicious." Visit at own risk) has established a standard of specifications for a common definition of "number matching" and can certify them according to their company's definition.
Major Components
The car's major not maching components are parts such as the engine, transmission, rearaxle assembly, and frame of the car. Many times these components contain dates, casting numbers, model numbers, VIN, stamped numbers, or codes that can match the original components that were on the car when it was new. In some cases intake manifolds, exhaust manifolds, body panels, and carburettors could also be considered major components.^{[4]}
Minor Components
Minor components are components that would not dramatically affect the overall value of a car, regardless of being original or not. These are parts that are commonly replaced due to regular wear and tear. Parts such as the interior fabric, paint, chrome trim, brakes, instruments, electrical components and wiring are considered minor components.
How does number matching work?
The numbers or casting dates on the major components of a car must be present and fall in a particular order.^{[5]} For example, an engine’s assembly date must come before the build date of the car, and the casting dates must come before the assembly date of the engine because an engine assembly date (the date the engine was assembled, usually at a different location) could not be after the assembly date of the whole car. Engines are assembled prior to being installed in the car at the factory. Therefore, the assembly date of the car would have to be after the assembly date of the engine. Casting dates (the dates formed in the metal of a component at the foundry) could not be after the assembly date of the engine. And casting dates would need to be well in advance of the assembly date of the engine. Numbers and dates help track an accurate history of how a car was built and when and where the car and the parts used to create the car were made.
If a car has number matching major components it helps define how collectible a car is. Number matching cars typically will have a much greater value than nonnumber matching cars.
Why are number matching cars collectible?
Number matching cars are collectible because they are much rarer than nonnumber matching cars.^{[6]} Number matching cars represent a look back in history at what was occurring in the automobile industry, and it may be for this reason that matching numbers are tied to collector car values.^{[7]}
References
 ^ www.numbermatching.com
 ^ #1 Motor Mart  Matching Numbers
 ^ Camaro Model Identification and Numbers Decoding
 ^ Confirming a Matching Numbers Vehicle  Automedia.com
 ^ Cars at Large: Numbers Matching: A definition and explanation (Part I); even you seasoned car guys might learn something!
 ^ Determining Matching Numbers
 ^ What is a "Numbers Matching" Classic Car
Categories: Automobile maintenance
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