Why Date Coding Matters for Mustang Restoration
The 1964½–1973 Mustang is one of the most copied, cloned, and counterfeited classic cars in the world. Because demand for numbers-matching cars is high and supply is finite, the financial incentive to alter components is significant. A correctly date-coded 289 HiPo engine block in a 1965 fastback can be worth £60,000–£80,000 more than the same block with a post-production replacement engine. That gap creates fraud.
Date coding isn't just for concours builds, though. Even if you're running a driver-quality restoration, knowing what you're fitting matters: a 1969-spec distributor on a 1966 car tells you something about the car's history. For buyers, sellers, and restorers alike, date codes are the most objective evidence available for establishing originality.
What This Guide Covers
Date coding in the Mustang context applies across a range of components. The major ones covered here are:
- Engine block — casting date on front left pad; assembly-line date on oil pad or timing cover
- Alternator (or generator on early 1964½ cars) — body stamping on rear face or housing
- Carburettor — top of main body or float bowl; Ford part number date suffix
- Distributor — body near the advance mechanism or vacuum unit
- Voltage regulator — usually on a stamped or printed label on the body face
- Radiator — top or side tank corner; sometimes on a tag rather than stamped
Not every component on every car will carry a legible date code — some were ground off during previous work, some never carried them. The process below tells you what to do in both cases.
How to Identify & Read Date Codes
The Ford Date Code Format
Ford stamped or cast a four-part alphanumeric code on most major components. The format:
| Position | Example | What it means |
|---|---|---|
| 1 — Decade letter | C |
A=1940s, B=1950s, C=1960s, D=1970s, E=1980s |
| 2 — Year digit | 6 |
Final digit of the production year (so 5 could be 1955 or 1965 — decade letter disambiguates) |
| 3 — Month letter | C |
A=January, B=February … L=December (I is skipped) |
| 4 — Day | 15 |
Day of month 01–31 |
Full example: C6C15 = December 15th, 1966.
On engine blocks specifically, a second stamp may appear on the block's oil drain-back pad or timing cover — this is the assembly line date, recording when the block reached the engine assembly line. It uses a different format and is not the same as the casting date. Both are valid for verification, but you need to know which one you're reading.
Where to Find Codes on Each Component
- Engine block — Front left face near the timing cover (casting date); oil pad on the side of the block near the front (assembly line date). On a small-block V8, check the timing cover mating surface and the passenger-side front rail.
- Alternator — Rear face of the body near the slip ring housing. You may need to remove the pulley to see it clearly. On early cars with generators, the date code is on the drive end frame.
- Carburettor — Top of the main body (primary), or on the float bowl for Autolite/Motorcraft units. The date code may appear as a suffix to the part number: e.g., D0AF-9510-BA (the suffix letters encode the date). Ford used a different date encoding on carburettors — decode carefully using Ford's published suffix table.
- Distributor — Body face near the advance mechanism, often on the lower body or side of thehousing. Some units also stamp the date on the vacuum advance unit mounting face.
- Voltage regulator — Usually on a paper or foil label affixed to the body, which can degrade over decades. Check the base as well — sometimes stamped directly into the metal.
- Radiator — Top-left corner of the header tank, or on a small metal tag crimped to the tank seam. Some radiators have the code cast into the tank metal; others have a riveted tag.
How to Read a Code Against Your Build Date
The fundamental rule: the component's date code should precede your vehicle's production date by days to a few weeks. The casting was made before the car was assembled. A gap of months is not automatically wrong — early production runs of a component can precede the car by weeks — but a date code that falls after the build date is definitive proof the component was replaced.
To establish your vehicle's build date, use your Marti Auto Works report (the single most useful document for any 1964½–1973 Mustang owner) or check the door jamb data plate. The door jamb plate is correct but less precise; Marti gives you the exact production date, plant, and assembly sequence number.
Restamped / Remarked Components — Name It Plainly
Restamping is deliberate fraud. Someone grinds off the original date code and stamps a new one to make a replacement component appear original. It is done to make money, and it is dishonest. You should know what it looks like.
Signs of restamping:
- Paint or filler over the stamping area — a thin layer of body-coloured paint applied to conceal the original stamping beneath. This is the most common tell. Hold a bright light at a shallow angle: paint over a stamp looks different from the surrounding metal surface.
- Uneven character depth — original Ford stamps were machine-punched and consistent in depth and pressure. A restamp is usually hand-struck; you can see some digits punched deeper or at a slight angle.
- Misaligned or inconsistent spacing — the characters on a restamped part may not line up on the same baseline or be spaced the same distance apart.
- Font style anomalies — Ford used a specific stamp font. If you have a known-correct reference stamp (from a same-year car, or from a photo in a parts catalogue), compare them. An obvious mismatch is grounds to walk away.
- Clean stamping on a dirty component — a date stamp that looks brand-new while the rest of the part is corroded, painted over, or covered in decades of oil is suspicious. Original stamps age with the part.
If you see signs of restamping on a component being sold as original, that's the end of the conversation about that part's authenticity. The seller either knows and is defrauding you, or doesn't know and has been defrauded themselves. Either way, do not pay a premium for restamped goods.
Original vs. Replacement — How to Tell
Not every non-original component is fraudulent. Many replacement parts were fitted correctly with correct-spec components — a 1968-spec replacement distributor on a 1966 car was a normal repair in period. The distinction matters:
- Original (date-code correct) — the date code precedes the build date by an acceptable window and the part is the correct specification for the model year
- Correct-type replacement — the date code follows the build date (proving it was replaced), but the part is the correct specification for the model and year. No fraud involved; normal maintenance history
- Incorrect replacement — a part from a different model year or spec was fitted. May be acceptable for a driver but penalised in concours
- Restamped / fraudulent — the date code has been altered to misrepresent the part's age or origin. Fraud, walk away from the numbers-matching claim
Ford's date coding system is one of the more straightforward ones once you know the format — a letter for the month followed by a single digit for the year. January 1966 is A6, December 1967 is L7. The confusion usually comes from people not knowing where to look rather than not knowing how to read the code once they've found it.
On the carburettor, the code is stamped on the float bowl — look for it on the driver's side face, sometimes obscured by fuel deposits. The alternator code is on the case, usually on the rear housing near the voltage regulator mounting point. Distributors carry the code on the housing just above the vacuum advance canister. If you're looking at a car where the seller claims all components are date-correct, check the carburettor first — it's the one most commonly replaced during the car's working life and the one most frequently overlooked during a numbers-matching restoration.
The other thing worth knowing: the date code should precede the car's build date by a few weeks at most. Components were manufactured and shipped to the assembly plant on short lead times. A carburettor dated six months before the car's build date is suspicious. One dated after the build date is definitely a replacement.
Decision Tree: Verify a Component's Date Code
Work through these three checks in order. Each one either clears the component or flags it for further investigation.
Upload a photo of the stamping to CarSpanner's chat with the component name and your vehicle's year. Geoff can help interpret the code and tell you whether it matches.
What Vehicles Does This Apply To?
The Ford date code system described here applies specifically to:
- Ford Mustang 1964½–1973 (all body styles and engine options)
The system was consistent across the model run, though the specific components carrying codes varied by year and specification — a 428 Cobra Jet engine has different stamping locations to a 200 cu in inline-six, but the encoding format is the same.
For other Ford models from the same era (Fairlane, Galaxie, Comet), the format is similar but not identical. The guide above is tuned to the Mustang; cross-model application requires verification against model-specific references.
Sourcing Date-Correct Mustang Parts
Date-correct NOS parts for 1964½–1973 Mustangs are specialist items. Availability is limited and prices reflect rarity. For most restoration standards, quality reproductions are appropriate; the date code chase matters most for concours-level builds.
Where to look
- National Parts Depot (NPD) — www.nationalpartsdepot.com — the largest US inventory of genuine Ford NOS and correct-spec reproduction components for 1964½–1973 Mustangs. Their online catalogue allows filtering by year and specification.
- Marti Auto Works — www.martiauto.com — build documentation, window stickers, and a curated selection of genuine NOS parts. Also the definitive source for verifying your own vehicle's build date via the Marti report.
- Scott Drake — www.scottdrake.com — quality reproduction parts specifically for 1964½–1973 Mustangs. Appropriate for driver and show standards; not NOS but correct spec and widely used.
- Classic Industries — www.classicindustries.com — large catalogue of correct-spec Mustang reproduction parts covering body, mechanical and interior.
Quality reproduction: when it's acceptable
For driver-quality and show-class restorations, quality reproductions from Scott Drake, Classic Industries, or NPD's own reproduction line are entirely appropriate. The replacement part is correct for the specification; the date code (while not original) doesn't affect the car's usability or its appearance to a non-concours judge. Budget accordingly: don't pay NOS prices for reproductions.
For concours builds, source NOS wherever possible. The JCNA and MCA scoring systems have clear rules on component originality; the difference between a correctly-dated NOS part and a quality reproduction is reflected in the judging score.
Not sure whether to pursue a NOS part or accept a quality reproduction? Our OEM vs NOS vs Reproduction guide explains the restoration standard trade-offs in plain terms.
OEM vs NOS vs Reproduction Guide →Geoff's Verdict
If you're building a numbers-matching Mustang for concours or investment purposes, date-correct components matter and there's no shortcut. Marti Auto Works is the place to start — their build records will tell you exactly what left the factory on your car, which gives you the date ranges you're cross-referencing against. National Parts Depot carries a good selection of date-correct NOS and correctly-coded reproduction components for the more common years.
For a driver-quality build, date coding is largely irrelevant. A correctly-specified carburettor that runs well is worth more than a date-correct one that needs rebuilding. Spend the money on function rather than provenance unless the car's value or your personal standard demands otherwise.
On eBay — there's genuine NOS Mustang date-coded stock available if you search specifically. Search by component and year rather than "Mustang NOS" and you'll find private sellers clearing old dealer stock. Verify the code before you buy and ask for photographs of the stamping. Some sellers don't know what they have; others know exactly what they have and price accordingly.