Two numbers tell the whole story of a T-Type — where to find them, how to read them, and what the codes mean.
Every MG T-Series left Abingdon with two identity marks the factory expected you to be able to find and cross-check: a chassis (car) number stamped into the frame, and an engine number on a plate on the engine itself. Together they tell you which model you are looking at, roughly when it was built, and — with a little decoding — how it left the works. This guide walks through where to find both numbers, how to read the chassis ranges by model, how to decode the TF's Nuffield car number, what the engine prefixes mean, and what to make of a replacement engine.
Reference information adapted from the MG Car Club T Register; verify your car's details with the T Register and the MG factory records held at the British Motor Museum.
Where to find the numbers
Two places to look, and they should agree.
Chassis number. Look at the near-side (left-hand as you face the front of the car) dumb-iron — the forward chassis extension the bumper mounts to. The chassis number is stamped directly into the metal. It is then repeated on a small identity plate riveted under the bonnet, typically on the battery/tool box or bulkhead. The stamped number and the plate should match; if they don't, you are looking at a car that has had frame or bulkhead work done at some point.
Engine number. On the TA, TB and early TC the engine number lives on a plate riveted to the left-hand side of the flywheel housing. The plate itself is worth noticing: an octagon, circle or square carrier with a small central brass disc that identifies the engine type. Later TCs and every TD and TF moved the engine number to a shallow machined plinth on the forward right-hand side of the block, where the number is also stamped directly into the plinth alongside the plate.
Always cross-check the two. Because these cars are now seventy or more years old and have passed through many hands, mismatched engines are common — a car with an original chassis and a period-correct but non-matching replacement engine is a perfectly normal thing to encounter, and not necessarily a mark against it. What you want to know is what you are actually looking at.
Chassis numbers by model
Chassis numbers on the pre-TF cars run as plain numbers, without a model prefix on the frame itself. Approximate production ranges are:
| Model | Chassis number range |
|---|---|
| TA | 0253 – 3255 |
| TB | 0252 – 0630 |
| TC | 0252 – 10251 |
| TD | 0251 – 29915 |
| TF (1250 + 1500) | 501 – 10100 (Nuffield numbering) |
A historian's caveat: the very first numbers in each series (0251 or 0252) were prototypes and are not generally counted as production cars.
TD variants: what "Mark II" and "TD2" actually mean
The TD is the model most often muddled by owners and by adverts, so it is worth being precise. There are two things that can look like the same thing and are not.
TD/C, or "Mark II". A factory competition-oriented variant of the TD with larger valves, larger carburettors and stiffer front suspension. It is a specification, distinguishing car from car.
"TD2" (as in the engine code XPAG/TD2/). A production change to the engine, not a competition spec. The TD2 code identifies the engines built after the introduction of the larger 8" clutch around chassis number 10000, in mid-1951. A perfectly ordinary, non-competition TD from late 1951 onwards will normally have a "TD2" engine number and is not a Mark II.
Two different things, two different meanings.
TD export codes
Export TDs also carry codes on the identity plate reflecting how they were shipped:
- EXR — export, right-hand drive.
- EXL — export, left-hand drive.
- EXLU, later EXL/NA and then EXLNA — the North-American specification LHD car as it evolved through production.
TF: Nuffield car numbers
The TF adopted the group-wide Nuffield car-numbering system used across Morris, MG and their sister marques. After two prototypes the sequence began at 501 and ran to 10100, comprising roughly 6,200 TF1250s and 3,400 TF1500s. On the chassis itself the stamping is normally prefixed TF; on the identity plate the number is the Nuffield car number and encodes rather more information than an early chassis number ever did — see the decoder below.
Decoding the TF Nuffield car number
The TF identity plate carries a car number in the form of two letters, then a first digit, then a second digit, then the sequential build number — for example HDP 15 xxxx. Each element means something specific.
Body type and colour (the two letters)
The first pair of letters describes the body type and factory colour.
| Letters | Meaning |
|---|---|
| HD | MG two-seater body |
| HDA | HD body, Black |
| HDB | HD body, Light Grey |
| HDC | HD body, Dark Red |
| HDE | HD body, Mid Green |
| HDP | HD body, Ivory |
First digit — market and drive
| Digit | Meaning |
|---|---|
| 1 | UK, right-hand drive |
| 2 | Export, right-hand drive |
| 3 | Export, left-hand drive |
| 4 | North America, left-hand drive |
Second digit — finish
| Digit | Meaning |
|---|---|
| 3 | Full cellulose finish |
| 5 | Primer (finished elsewhere) |
| 6 | Cellulose body with synthetic wings |
Worked example
A TF whose plate begins HDP 13 xxxx reads as: HD body (MG two-seater), P for Ivory, first digit 1 for UK right-hand drive, second digit 3 for full cellulose finish. In plain English: a UK-market, right-hand-drive, Ivory TF, fully cellulose painted.
Two small things to keep in mind. The identity plate carries the Nuffield car number; the chassis stamping on the frame is normally the TF prefix plus the sequential build number, and the two point to the same car. CKD (completely knocked-down) or partially-assembled export cars can carry additional letters from the Morris-standard scheme reflecting their shipped state, so an unfamiliar extra letter on a TF plate is not necessarily wrong. Treat any decode as an indicative guide and confirm with the T Register or the factory records.
Engine numbers and what the prefix tells you
The engine-number prefix identifies the engine type and, for XPAG-engined cars, the specific evolution the block represents. At the highest level:
| Model | Engine family |
|---|---|
| TA | MPJG (unique to the TA) |
| TB | XPAG |
| TC | XPAG |
| TD | XPAG |
| TF 1250 | XPAG |
| TF 1500 | XPEG |
Within the XPAG family, the T Register's ongoing work identifies distinct sub-types by the number-prefix carried on the plate, which reflects two production changes — clutch size (7¼" or 8") and water-jacket porting (oval or round water holes).
| Prefix | Model / spec | Water holes | Clutch |
|---|---|---|---|
| XPAG/ | TB, TC | Oval | 7¼" |
| XPAG/TD/ | TD, TD Mk II | Oval | 7¼" |
| XPAG/TD2/ | TD, TD Mk II | Oval | 8" |
| XPAG/TD3/ | TD Mk II | Round | 8" |
| XPAG/TD2/ | TD (late) | Round | 8" |
| XPAG/TF/ | TF 1250 | Round | 8" |
| XPEG | TF 1500 | — | — |
Two useful footnotes. Export LHD cars often carry an extra code LHX appended to the engine number (for example XPAG/TD/LHX …); this normally appears on the bulkhead identity plate rather than on the engine plate itself. And because the MG Y-type saloon and tourer shared the same basic XPAG unit in a milder state of tune, Y-type engines occasionally end up in T-Types and vice versa; their prefixes follow a related but distinct scheme, so an unexpected Y-related code is worth investigating rather than dismissing.
Replacement engines and casting numbers
Many surviving T-Types no longer wear the engine they left Abingdon with. Morris Motors and later BMC supplied factory-exchange "Gold Seal" replacement engines throughout the T-Series's usable life, and any car that saw hard use — as most did — is a candidate to have received one.
A replacement engine is easy to identify by its plate. Instead of the octagonal or circular XPAG plate the car was built with, it typically carries a square "replacement engine" plate with a letter prefix (letters recorded to date include A, B, C, E, G and RS) followed by a longer serial number. The original engine number is sometimes still to be found stamped directly into the block near the plate, if a previous owner has not filed or dressed it away — worth a careful look with a torch and a wire brush.
Casting numbers and date codes
Beyond the identity plate, the block and head carry raw casting information from the foundry. On XPAG and XPEG blocks the casting number is generally found near the dipstick tube; on the head, similar casting information sits toward the rear. Small features such as the "W-in-a-diamond" foundry mark appear on later blocks and heads, and the T Register has done extensive work correlating casting numbers, date codes and foundry marks to build periods. The blocks themselves were cast at the Wellingborough Ironworks.
The complete casting-number picture is much more detail than belongs in this guide. For serious dating and originality work, the T Register's ongoing casting-number research is the reference to use.
Why it matters, and how to verify
Matching numbers matter for two reasons. Originality and value: a car whose chassis, bulkhead plate and engine number all agree, in the correct format for the model, is more valuable — and more informative — than a car that has been re-engined or rebadged over the years. Historical accuracy: knowing exactly what you have (a genuine TD Mk II, a TF1500 rather than a TF1250, an original XPAG rather than a Gold Seal replacement) lets you set the car up correctly and describe it honestly.
That said, a T-Type that has had a replacement engine along the way is a perfectly normal thing. These are cars meant to be driven; a sound, correct-family Gold Seal XPAG in a TC is not a problem, only a fact about the car. What matters is knowing.
For definitive verification of a specific car's history there are two authorities to consult:
- The MG Car Club T Register, custodians of the community-held knowledge on chassis and engine numbers, casting numbers and variants — visit mgcc.co.uk.
- The MG factory records, held at the British Motor Museum at Gaydon, which can confirm the original build details of a car by its chassis number.
If you have decoded your own T-Type from this article, please add it to the Registry — every submission strengthens the record for the next owner.
Frequently asked questions
Why does my tuned XPAG misfire under load?
Misfire under load is almost always ignition on an XPAG, not carburation. Check the plug gaps and colour first — sooty plugs mean the mixture is rich or the ignition is weak; white or blistered electrodes mean it is lean. Then confirm the points gap and dwell, the rotor arm and condenser, and that the coil is producing a strong blue spark. On a Stage 1 or Stage 2 engine, also check the static timing has not crept too far advanced; a pinking engine often feels like a misfire and will eventually burn a hole in a piston. Finally, balance the SUs again — an unbalanced pair can leave one cylinder running lean enough to misfire at wide throttle.
Why does my XPAG hesitate when I open the throttle?
Hesitation on pick-up is the classic SU weak-mixture signal. The piston in the carburettor is lifting too fast for the fuel to follow, usually because the jet is set too lean, the needle is worn, or the dashpot oil is too thin. On a Stage 1 car with standard 1.25 in SUs, start by checking the damper oil level and weight — SAE 20 is correct — and that the piston rises smoothly without sticking. Then richen each jet by one flat, test again, and confirm with the lifting-pin method. On a Stage 2 car with 1.5 in SUs the same rule applies, but the needle profile is more critical; a worn or mismatched needle will hesitate whatever the jet setting.
Why is my tuned XPAG hard to start when hot?
Hot-starting problems on a tuned XPAG usually come down to fuel evaporation or flooding. A free-flow exhaust and a hot engine bay can boil the fuel in the float chamber and carburettor body, making the mixture over-rich. Check the float level first — it should be at the workshop-manual figure, not simply "looks about right". If the car starts cold but floods hot, try easing the throttle fully open while cranking to clear the cylinders, then start with no throttle. On Stage 2 engines with raised compression the starter also has to turn a higher-compression engine against a hot block; a good battery and clean earth straps matter more than on a standard car.
My Stage 1 XPAG pings on acceleration — what do I adjust?
Pinking means the combustion pressure peak is arriving too early. On a Stage 1 tune running on modern 95 RON petrol, retard the static timing by one or two degrees first and re-test on a warm day under load. If it still pings, check that someone has not already advanced the distributor beyond the Stage 1 figure, verify the compression ratio has not been raised by a previous skim, and make sure you are not running the engine below about 1,500 rpm in a high gear. Do not simply richen the mixture to mask pinking — it helps a little, but the real fix is timing or compression.
After fitting 1.5 in SUs my Stage 2 idle hunts — what is wrong?
An uneven idle after a Stage 2 carburettor swap is usually one of three things: the throttle spindles are worn and drawing air, the inlet manifold is not matched to the head ports and is causing reversion pulses, or the jets and needles are not centred and matched. Re-check the manifold face and gasket match, recentre both jets with the piston-drop test, and confirm both carburettors are drawing the same airflow at idle. Stage 2 engines with a fast-road cam also have less manifold vacuum at idle, so the idle speed may need to be set a little higher than standard — typically 800–900 rpm — to keep the SUs stable.
How do I know if my tune is running lean?
Lean running shows up as a flat spot under load, popping in the exhaust on the overrun, white or grey spark-plug insulators, and elevated exhaust-manifold colour after a run. On a rolling road the air/fuel ratio will read above 14.5:1 at cruise or above 13.0:1 at wide throttle. Fix it by richening the mixture a flat at a time on the SUs, checking for air leaks around the manifold and balance pipe, and confirming the fuel pump is delivering at least 1.5 psi at the carbs. Lean mixture is the fastest way to burn exhaust valves on a tuned XPAG, so do not ignore it.
Related reading
For the coachwork side of identifying and looking after a T-Type, see the MG T-Series Bodywork pillar article. For a walk through each model as a whole, The Models is the place to start; the Registry collects owner-submitted cars decoded exactly as described above.
Frequently asked questions
Where is the chassis number on an MG T-Type?
Stamped into the near-side (left-hand) dumb-iron — the forward chassis extension the front bumper attaches to — and repeated on a small identity plate riveted under the bonnet, typically on the battery/tool box or bulkhead. The stamping and the plate should match.
What engine does an MG TF1500 have?
The XPEG, an enlarged 1,466 cc development of the XPAG used in every other T-Type from the TB to the TF1250. TF1500 engine numbers are prefixed XPEG; a TF with an XPAG/TF/ prefix is a TF1250.
What does XPAG mean?
XPAG is the factory code for the T-Series' 1,250 cc four-cylinder overhead-valve engine, used in the TB, TC, TD and TF1250 (and in the sister MG Y-type saloon and tourer). XPEG is the 1,466 cc TF1500 development of the same basic unit.
How do I decode an MG TF car number?
Read it in four parts: the letters (body type and colour — HD is the MG two-seater, followed by A/B/C/E/P for Black, Light Grey, Dark Red, Mid Green or Ivory); the first digit (market/drive — 1 UK RHD, 2 export RHD, 3 export LHD, 4 North America LHD); the second digit (finish — 3 cellulose, 5 primer, 6 cellulose body with synthetic wings); and finally the sequential build number.
How do I tell a TF1250 from a TF1500?
By the engine-number prefix on the engine plate. A TF1250 carries XPAG/TF/; a TF1500 carries XPEG. Externally the two look almost identical, so the engine number is the reliable answer.
What is a TD Mark II?
The factory competition-oriented TD/C, with larger valves and carburettors and stiffer front suspension. It is a car-level specification, not an engine code — do not confuse it with the TD2 engine prefix, which simply marks the introduction of the larger 8" clutch in mid-1951 and applies to ordinary TDs as well.