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You are here: Home Tech Articles General How to Decipher FoMoCo Part Numbers - Overview
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How to Decipher FoMoCo Part Numbers - Overview

Note 1: Part (or service) numbers (used for ordering and inventory purposes, and marked on parts boxes, tags and labels) should not be confused with engineering or casting numbers (normally stamped on or cast in the part for identification during the manufacturing process). They are not interchangeable -- however all follow the same general rules, so these charts may be used to provide approximate interpretations of all types of these markings.

Note 2: There are two distinctly unique yet similar Ford identification numbering systems: 1950-1998 and 1999-present. This tutorial will obviously stick with the earlier system.


     Ford part numbers are divided into two main categories: Engineering Numbers and Service Numbers.

     The engineers will design a part and assign it an Engineering part number, which is an alphanumeric reference code used by the assembly plants. When the part is redesigned, the change needs to be noted so the Engineering part number is changed. When the part is released for service it is assigned a Service part number. It is a different number, because how a part is finished and packaged for service is different from its original production counterpart. (It's the number used by your Ford parts man to look for your order. He doesn't want to know about the engineering part number. However, you may need it because the engineering number is the one appearing on many parts.) This allows Ford Parts and Service to track changes affecting interchangeability by modifying the Ford Service part number. The Service part number will not change with the Engineering part number unless the change affects interchangeability. Therefore, the part numbers on the part are generally Engineering numbers while the Service part number will be on the box. There are some exceptions, such as a whole grouping of parts or a kit. Engineering and Service numbers decode the same way. The difference being the fourth character of the prefix.

     Part numbers consist of a prefix, a basic part number, and a suffix. An example would be F4ZZ (prefix), 6E086 (basic part number), -A (suffix).

     You can use these numbers at swap meets or salvage yards to match to existing numbers you might have. You know if the basic number is the same it should be compatible if the suffix number on the part you are comparing is a later alpha character than the existing one. Early suffix designations generally begin with "A" and increment through the alphabet as design changes are made that affect interchangeability. If the suffix on the part you were looking to replace (your existing part) was an "A" you could use parts with have a "B" suffix. If the part you were looking to replace (your existing part) had a "B" suffix, a part with the "A" suffix would probably have a compatibility issue. Parts that have later suffix codes are the ones to get.

Regular part numbers (other than hardware parts) are coded in two basic ways:
  • Regular parts have a four character prefix (LFLL), a four or five digit part number, and a one-letter suffix.

    Example: C5ZZ-5255-F (Exhaust "turn-down" tailpipe on '65-66 289 4V Non-GT Mustangs)

  • Many body-style specific sheet metal, body, interior and trim parts use seven digits in the part number, the first two of which identify the basic body type application, with the last five ("Body Group") identifying the specific part within a general body area. A three-letter suffix may be used, usually to indicate color.

    Example: C6ZZ-6504290-BAB (Instrument Panel, 1966 Mustang, Black)

Hardware parts (fasteners, clamps, grommets, plugs, fittings and similar items) are numbered under two slightly-different systems. CLICK HERE for more info.

Yet another numbering system is used for Ford Special Service Tools. CLICK HERE for more info.

The Prefix

     The four-digit alphanumeric prefix tells the year the part was released for production, the vehicle line the part was originally released for and by what Ford engineering division (chassis, engine, body, etc.) or in the case of a service parts, the Ford car division the part is for - Ford or Lincoln-Mercury.

  • The first character of the prefix indicates the decade of design, starting with "A" for the 1940's, B for the 1950's, C for the 1960's.

  • The second character of the indicates the year within the decade, "C5" would be 1965, "F4" would be 1994.

  • The third character of the prefix indicates the product part the part was originally designed for, with few exceptions. Note that "outside sales (code F), "Motorcraft Brand" (code P), or imported parts from Ford of Europe (code R) are identified with their product line code in the third position.

  • The fourth character indicates the part source, whether it is product engineering office or service part.

Let's decode a part number prefix, using the example posted above:
-5255-F (Exhaust "turn-down" tailpipe on '65-66 289 4V Non-GT Mustangs)

NOTE: The following info doesn't apply to hardware or tools:

First Digit: Decade      (EXAMPLE: C5ZZ)

A = 1940's (often omitted)
B = 1950's
C = 1960's
D = 1970's
E = 1980's
F = 1990's
Second Digit: Year Number      (EXAMPLE: C5ZZ)
Last digit of year of introduction or revision. This number corresponds to the decade shown in the first digit. Thus C5 = 1965.
Third Digit: Model      (EXAMPLE: C5ZZ)
A = Ford (Generic) / Galaxie (1958-later)
B = Bronco (1970-73), Maverick (1975-77), Fairmont (1978-83)
C = Remanufactured Parts (1966-75), Elite (1975), Capri (1979-later)
D = Falcon (1960-69), Maverick (1970-74), Granada (1975-82), LTD (1983-later)
E = Truck (Cab over Engine) (1970-73), Pinto (1976-80), Escort (1981-later)
F = Foreign sales / Trans Am Racing
G = Comet (1961-67), Montego (1968-76), EXP (1982-later)
H = Holman/Moody HiPo Part, Heavy Truck (1966-82), Medium Heavy Truck (1983-later)
J = Industrial / Marine engines
K = Edsel (1958-60), Tilt Cab (1970-73), Comet (1975-77), Zephyr (1978-83), Marquis (1983-later)
L = Lincoln (1958-60), Mark (1961-later)
M = Mercury (1958-later)
N = Tractor (1958-later)
O = Fairlane (1962-68, Torino (1969-76), LTD II (1977-79), LN7 (1982-83)
P = Autolite (Later Motorcraft) (1962-later)
R = Rotunda (Generic)(1962-69), Ford of Europe (1970-later), Remanufactured Parts (1976?-later)
S = Thunderbird (1958-later)
T = Truck (1958-65), Light/Medium Truck (1966-82), Bronco (1966-82, Except 1970-73), Light Truck & Bronco I (1983-later)
U = Econoline/Club Wagon Van (1961-later)
V = Lincoln Continental (1961-81)
W = Cougar (1967-80), XR7 (1981-82), Cougar (1983-later)
X = Truck (Short Highway) (1970-73)
Y = Meteor (Canada) (1962-72), Bobcat (1975-80), Lynx (1981-later)
Z = Mustang 1964-73; Mustang II 1974-78; Mustang 1979-later
2 = Pinto (1972-75)
3 = Tempo (1984-later)
4 = Comet (1971-74), Monarch (1975-80), Cougar (1981-82), Marquis (1983-later)
5 = Recreation Vehicles (1974-75), Continental (1982-later)
6 = Pantera (1971-75), Topaz (1984-later)
7 = Courier (1971-82); Ranger/Bronco II (1983-up); Explorer (1991-later)
8 = Capri (U.S. Parts) (1972-75)
9 = Turbine Engine Parts (1970-75)
Fourth Digit:  Design Engineering Office       (EXAMPLE: C5ZZ)

A = Light Truck Engineering Division
B = Body and Electrical Product Division
C = Chassis
D = Overseas Product Engineering
E = Engine
F = General Parts/Electrical and Electronics Division
H = Climate Control (1972-up)
J = Autolite/Ford Parts & Service Division
L = Industrial Engine Parts & Service
M = Performance/Special Vehicle Operations (Incl. Holman Moody)
N = Tractor Parts
P = Auto Transmission
R = Manual Transmission
S = Light & Heavy Truck Special Order Parts
T = Heavy Truck Engineering
U = Special Vehicle Operations
W = Axle and Driveshaft
X = Emissions, Economy and Special Vehicle Engineering (Muscle Car Parts)
Y = Lincoln/Mercury Service Parts
Z = Ford Service Parts

The Basic Part Number

     Regardless of whether it's an engineering or a service part number the basic part number will be the same. A basic part number is included within the casting number and indicates what the part is, not what it was made for or when it was made. An example could be a master cylinder - most master cylinders have a basic part number of 2140, but there a number of different master cylinders for different Ford vehicles. They all are master cylinders however, and share a basic part number. For example, 6049 is for all cylinder heads, 6303 is for crankshafts and 6010 is for blocks. The number for the casting used for machining these parts is different. Referring to the cylinder head again, the basic finished part number is 6049, whereas it's casting number is 6090. Because it is relatively easy to put a casting number on a part while it is being case, it's the casting number that appears on the part - great for them and terrible for the guy trying to identify a part. Also, the number that appears on a casting may not include the basic casting number for the simple reason that you don't need a number to tell you you are looking at a block or intake manifold. The number generally consists only of the prefix and the suffix, or C70E-C for the cylinder head.

     Parts that have to do with the body of the car will have the body code at the beginning of the basic part number, as in this example, D0AZ-6543720-A (a trunk weatherstripping.) 65 is the body code part of the basic number which specifies A Mustang hardtop. Other body code designations are as follows:

  • 25 = Luggage Rack
  • 50 = Mercury
  • 53 = Lincoln
  • 54 = 4-Door
  • 57 = Ford
  • 60 = Ford
  • 62 = 2-Door Sedan/Coupe
  • 63 = 2-Door Hardtop (Mustang Fastback)
  • 65 = 2-Door Hardtop (Mustang)
  • 66 = Ranchero
  • 71 = Wagon
  • 76 = Convertible
  • 81 = Truck
  • 83 = Truck
  • 87 = Truck
  • 89 = E100
  • 91-99 = Bronco


     A part-number suffix generally tells you the change level of a part, regardless of whether it is applied to the casting, the finished part or the service part. A suffix of A applies to a part produced as it was originally designed, B indicates it was changed once, C indicates it was changed twice and right through the alphabet in sequence, excluding the letter I. When the alphabet as been gone through once, the suffix grows to two letters and starts over as AA, AB, AC and so on.

     How does a change affect the other two numbers? A service part and its number can change independently of the casting part and its number simply because it comes after these two in the scheme of things. Using the same reasoning, a finished, or engineering part can change independently of the casting, but not of the service part. A casting affects both the finished and the service parts. This is why the suffixes of all three numbers rarely match.

     However, sometimes a single letter indicates specific application. For example: 9425-A is an intake manifold for a 289-2V engine, whereas a 9425-B is for a 289-4V engine, and a 9425-C is for a 351C-4V engine.

     The suffix can also refer to the color or finish of the part, or the left- or right-hand use of a part. In most cases if the part is for left-hand use, the basic number ends in a odd number and the basic number for the right-hand part ends in a even number. For example, the 1969 Mustang front fender wheelhouse molding C9ZZ-16038-A  is the right-hand molding and C9ZZ-16039-A is the left-hand molding. Notice there is no body code in front of the basic number 16038. The reason for this is that a change in body style did not effect the application of this part...that is, all '69 Mustang body styles used the same wheelhouse molding.

These tables are by no means all-inclusive, and I would gladly welcome your comments or corrections. Please e-mail me at


You are here: Home Tech Articles General How to Decipher FoMoCo Part Numbers - Overview

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