Matching numbers.

"Matching numbers" is two words doing an enormous amount of work in a classified advert. All it means is that the numbers stamped on the car agree with each other and with what the factory recorded. We had a checker here that said they did, with a score attached, on data covering two families and a handful of years. The score could beat its own ceiling. This page is what is left when you take the score away: which numbers to write down, where each one is stamped, and what a checker would have to show you before it was worth anything.

What works today

What is a concept

The checker that stood here has been withdrawn. It held two families out of five, a handful of years, and a score that could rise above its own top mark.
Nothing on this page compares anything. There are no fields, no result and no score.
VWX does not decide whether a car is original. The factory record does that, and we are not it.

The four numbers, and where they are stamped.

Before anyone can tell you anything, you need these four written down. This part does not need a tool. It needs a torch and twenty minutes.

Chassis number: On your data plate or frame head.
Engine stamp: Engine case, near the oil filler.
M-Code: From your data plate.
Month built: Also on the data plate.

Photograph all four before you touch them with anything. A wire brush has ended more arguments about originality than any tool on this site ever will.

What matching actually means.

The engine agrees with the year.: The letters on the case belong to a code the factory used while your car was being built. An engine that does not agree is not a scandal. These cars are sixty years old and engines get tired.
The chassis number agrees with the family and the year.: The shape of the number, and where it falls in the run. This is the number that is hardest to argue with and easiest to misread.
The plate agrees with the car.: An M-code for a sunroof on a car with no sunroof is not a mystery. It is a plate from another car.

None of that adds up to a verdict, which is why the old page's four headlines have gone. Numbers agree or they do not, one at a time, and the interesting cars are the ones where two of them disagree and there is a reason.

What we withdrew, and why.

The checker ran on one file of hand-entered production data with no source on it. Stated plainly, this is what it held.

Two families out of five.: Type 1 and Type 2. A Type 3, a Ghia or a Thing got "we don't have data for this one yet." for every number you gave it.
Six engine codes, then four.: Six for the Type 1, four for the Type 2. That is not a reference. That is a sample.
Twelve chassis years, then five.: Twelve for the Type 1, five for the Type 2, with gaps in the middle of both. A number outside them read as a mismatch when it was really our shelf being empty.
Five option codes.: Type 1 only, and none for anything else on the list.
A score that could beat its own ceiling.: The points were divided by the number of checks and then multiplied by four, so one field agreeing on its own came out above the top of the scale. The number was printed anyway.

It also told you a check had failed when it turned a number down. There was no such check. Everything the page did was a lookup in those tables, and no table named where it came from.

Two things worth keeping.

A checker like that would be a good start, not the final word.
For paperwork you can hold, talk to a Volkswagen specialist, or ask Volkswagen Classic Parts for the factory record.

A checker built on historical data is only ever as good as the data. When it matters, the factory record is the document. We are not.

Written example — not analysis output

What a sourced note would read like.

The letters on your engine case are a code the factory used for this type, across a span of years that includes the one stamped on your plate. The span is named below, with its source.

Your chassis number falls outside every range we hold for that type and year — and we hold very few of them. That is a gap on our shelf, not a finding about your car. It is written that way round on purpose.

Source: named for each line above, or the line is not printed at all.

What this does not tell you: nothing here says the car is original, and nothing here says it is not. Two of four numbers agreeing is a fact. What it means is a conversation with someone who has their hands on the car.

Envisioned

A comparison that shows each rule it applied and where the rule came from.
Silence where the evidence is thin, instead of a number in a circle.
Coverage stated at the top: which families and which years are actually held.
An answer that ends at the factory record, not at us.
VWX will not authenticate a vehicle, and will not share anyone's contact details without their consent.

Tell us what you think

Which numbers on your car have you never been able to check?
What would a checker have to show you before you trusted it?

Concept

Chassis numbers.

The chassis number is the one thing on the car that was never meant to be replaced. It is the first thing anyone asks you for, and the last thing anyone can check. We had a decoder here. It read numbers against three tables nobody had sourced, and it turned down one of its own worked examples, so we took it down. This page is what stands in its place: where the number is, what its parts are, and what a decoder would have to cite before it said a word.

See the idea