Zitat:Some people are very concerned as to whether their Thunderbirds are totally original. Matching numbers are important to many. Many Corvette enthusiasts, for example, require that not only the right engine size be installed but that all parts have proper date codes or identification, i.e., "matching numbers". Currently, most Thunderbird judging requires only that the correct size engine be installed. As we move toward the more critical but optional orginality checks during judging, it is important to know the Ford part marking system. We cannot duplicate General Motors judging because GM assigned the same serial number to the chassis, motor and transmission where as Ford did not assign serial numbers to engine or transmission. Checking Ford part markings to insure that the parts are original is not possible. All we will be able to determine is that it is absolutely not original or that it might be original.
Ford uses two distinct but similar part numbering systems. "Engineering" and "service" numbers are both made up of a prefix, base number and suffix. Engineering numbers are issued first and when the part is released for production, a service number is assigned. The service number is what your local Ford parts department uses to order and stock parts. The engineering number is the number that is cast, stamped or otherwise identified on the part and is used by Ford during the design and manufacture process. This article will describe the engineering number generally found on the part. Ford used serial or "boxcar" numbers as engineering numbers in 1957 through and including a portion 1959. These will not be discussed. "C6MA 1130 A" is a made-up but representative engineering number (for all but "boxcar" numbers) and will be used below to explain the significance of each digit.

The Prefix "C6MA"
Ford used a three-digit prefix prior to 1957 that generally follows the ground rules of the four-digit code provided below. The four-digit prefix has been used since mid-1959. Ford used a variation of the four-digit prefix as identified below for a short period during 1959. This variation was that the third and forth digits were reversed. A six-digit prefix has also been used. The six-digit prefix is formed by preceding the four-digit prefix with "RF" (rough finish) for an unmachined casting or forging or with "X" for an experimental or prototype part. .
The first digit represented by "C" in the sample prefix provides the decade of the car model that the part was originally designed to fit. Parts built in the Fifties would have a letter "B", sixties - "C", seventies - "D", eighties - "E" and nineties - "F". .
The second digit represented by "6" provides the year of the car that the part was originally designed to fit. This digit is a single number between zero and nine inclusive. When taken with the decade ID it is possible to determine which year model the part was originally designed to fit. "C6" in our example would be 1966. "D0" would be 1970. It should be noted that a part designed for a 1965 for example would retain the "C5" identification on subsequent models (1966, 1967, etc.) until the design of the part was significantly changed. .
The third digit represented by "M" generally identifies the model of car (car line) for which the part was designed. A part designed for a Galaxy (big Ford) could also be used on a Thunderbird. The assignment of this digit was based on which model was planned for higher production. The bottom line is that all parts used on a Thunderbird may not be identified with the Thunderbird "S". This identification letter should not be confused with the model codes used in the parts' manual. The following list provides the codes:

A = Full size Ford
C = Remanufactured part
D = Falcon
F = Outside sales
G = Montego / Comet
J = Industrial engine
K = Edsel
L = Lincoln Mark-
M = Mercury
N = Tractor
O = Fairlane / Torino
P = Autolite part
R = Rotunda part
S = Thunderbird
V = Lincoln
W = Cougar
Z = Mustang


The Forth digit in the prefix as represented by "A" identifies the engineering activity responsible for the design. The engineering activity code as listed below should correspond to the base number; i.e., an engine component would not carry a "B" code. The following list summarizes the codes: .
A = Chassis
B = Body
C = Chassis after 1970
D = '60--61 Falcon or '62-up Overseas distribution operation
E = Engine and foundry
F = Engine fuel and electric
G = General parts
H = Climate control
J = Autolite
P = Automatic transmission
R = Manual transmission and steering
S = '60-'61 T-bird or '62-up light truck product
T = Heavy truck product
W = Transmission and axle
X = Special performance (Muscle parts '69-'72)
Y = Lincoln & Mercury part numbers as identified in parts' manual (Distribution)
Z = Ford part numbers as identified in parts' manual (Distribution)

The base number "1130"
The base number is one that is assigned to specific type parts, i.e., a wheel cover would be "1130" and an engine block would be "6015". The base number may not be identified on the part itself. Base numbers are assigned by category, but there are too many numbers to list. The categories are provided below with an example number: .
1000 - 2999; Wheels & brakes related (wheel - 1007, rear brake drum - 1126)
3000 - 4999; Front suspension, steering, rear axle & drive shift related (power steering pump - 3A696) It should be noted that on occasion Ford assigns a letter in the base number sequence to accommodate new numbers.
5000 - 5999; Frame, exhaust system & springs related (front coil spring - 5310)
6000 - 6999; Engine related (crankshaft - 6303)
7000 - 7999; Transmission & clutch related (automatic transmission case - 7005)
8000 - 8999; Cooling system & grill related (water pump - 8501 or 8502)
9000 - 9999; Fuel, carburetor & accelerator related (carburetor - 9510)
10000 - 12999; Charging & starting systems & distributor related (alternator - 10346)
13000 - 15999; Lamps & wiring related (tail light lens - 13450)
16000 - 16999; Fender & hood related (left front fender - 16006)
17000 - 19999; Speedometer, windshield wiper, bumper & accessories related (A/C compressor - 19703) .
Body parts have a base number but with a slight variation. The first two digits represent the body code as listed on the cars' data plate, i.e., 62 = two door sedan, 54 = four door sedan, 76 = convertible. The next five digits identify a unique type of part, i.e., a left front door = 20125.

The Suffix "A"
The suffix indicates the revision level of the design and also allows for further identification for alternate styles, colors, sizes, finishes, etc. Ford changed to a dual suffix system with the 1971 model. The suffix may be an alpha-numeric number.

Other Identification
In addition to the engineering number that may be found on a part, a date marking may also be provided. An example of a date code is "5 E 06", where "5" represents the year, "E" represents the month and "06" represents the date. "5" represents 1955, 1965, 1975, etc. in the example. "E" represents May. (January = A, February = B, March = C and so forth, except "I" is not used, so September becomes "J"). "06" is the date as listed on a calendar, that is, "06" represents the sixth day of the month. .
Using date codes, casting numbers and some deductive reasoning it is possible to determine if a part could have been the originally installed component. The prefix on the casting and the date code should always yield a date that precedes the date code of the car. .
Major components such as the engine, transmission and rear end may also have a tag with additional coding. These codes uniquely identify the components for installation on specific vehicles. A Parts' manual would be required to identify specifics for the tag information.

 
by Robert Pontiff