Proving the Numbers Match on a Vintage Jaguar XKE - Authentication

As vintage cars increase in value owners are more and more concerned over authenticity.  In my opinion, authenticity has several components:

• Ideally, a car should retain all the major components it was built with – engine, transmission, rear axle, body, and frame.  If parts have been changed in service the replacements should be exact matches.  Major components should be traceable by serial number to original factory records.
• The car should have the major equipment is was built with, and drive as when it was new.  It should not have been updated or modified, if presented as an original car.  If it’s shown as a modified car, all bets are off.
• The chassis should be dimensionally accurate and possessed of the same strength as when new. That means it’s not deformed by accidents and it’s not weakened by rust.  

Note that a car can be original or restored, and be authentic or not.  Those things are independent of one another.  An authentic car is not necessarily a high scoring car in concours.  A high scoring car is probably authentic, but not always, depending on the judging standards in use.

Authentication is therefore an additional thing one does; it's not a replacement for restoration or preservation work. That said, many people would have second thoughts about making major investment in an original-style car that is not authentic.  Someone building a hotrod or modified might not have those concerns.

One of the first things we do when authenticating a car, is check the serial numbers against the manufacturer’s records.  Here’s an example of what that involves on a 1973 Jaguar XKE.  As you will see, it’s no small undertaking.

We start by reading the builder’s plate under the hood.  On a vintage Jaguar that plate gives the car number – what we now call the vehicle identification number or VIN – plus serial numbers for the engine, body, and transmission. The plate is either on the firewall (V12 cars) or by the battery (6 cylinder cars)  It looks like this:

The engine serial number is visible without disassembly.  On a V12 car it’s at the rear of the motor, on top, between the cylinder banks.  It’s easy enough to check this number against the builder’s plate.

You can see the engine production date above the engine number.  If you have the factory record this date should be a bit earlier.  In this case the engine was built September 28, 1972, and the factory shows the car being finished December 19.

The body number is also shown on the builder’s plate, and it can be found on a riveted tag in back, often under the bumper.  Some disassembly is required to see the rear body tag.  The lower photo shows the tag to the left of the tail lamp opening.  As you can see, the body has been stripped in this photo.

The car number and type should be stamped in the firewall by the brake booster.  This stamping can only been seen after the booster and heater box have been removed.  This is what an original number will look like.  As you can see it’s a hand stamping and the metal is dented in.  It’s clear this is an original, unaltered stamp.

These numbers may be hard to read, and they may initially be hidden by paint and undercoat.

In this illustration ES3V12 denotes E Type, Series 3, V12 engine.  UD1S21644 is the car number.  If you find a car where these numbers are not a match for the underhood plate, you are likely looking at a stolen car.  The firewall number is hard to change, and unknown to most people.  In comparison, body tags and vehicle data plates are easily replaced, and blank plates are readily available.  

The final number to be matched to the underhood plate is the transmission number.  In most cases the transmission has to come out in order to clean off the top cover and read the number.  In this car, the number on the gearbox matches the number on the plate.

This appears to be a car where all the major components match, but we can’t rest just yet.  Since the plates are available blank there is always a possibility someone stamped a new one with the components that happen to be on this car.  The only way to tell is by checking factory records.

To do that, write the Jaguar Land Rover Trust in England.  For a modest fee they will check the numbers you supply against the factory records. In this case the car checked out, and is indeed original.

We also measured body dimensions and verified the car is straight.  It’s not weakened by rust, and it’s not otherwise modified.  This is an authentic 1973 XKE.

There are two other tags on an XKE of this vintage. There is a sticker in the door jamb, and a riveted tag under the windshield frame. These tags are commonly removed and replaced by restorers and are not themselves evidence of authenticity, though they need to be there for state motor vehicle inspection.

In the photo above you can see the door jamb label is in rough shape.  We can now print replacements for these labels so we're not concerned about that in restoration.  The underwood plate can be refinished but will otherwise remain original.

When you write the Jaguar trust to check numbers you will have to supply the numbers that are on the car now.  When we make requests we send photos.  Many car manufacturers will only confirm or deny the match of numbers you send; they will not just tell you what the numbers should be because they don't want to facilitate counterfeiting.

That means you need to do some considerable teardown to make a request, if you want all the numbers verified. What we do is start simple - we verify the car and engine numbers go together and if that's an initial match we dig deeper.  The engine is the most likely part to be replaced or upgraded.

This post is specific to the Jaguar XKE but most other cars are similar in how they are numbered, though number schemes and locations vary.

(c) 2018 John Elder Robison

John Elder Robison is the general manager of J E Robison Service Company, celebrating 30 years of independent Jaguar, Bentley, Rolls-Royce, BMW/MINI, Mercedes, Land Rover, and other vintage restoration and repair in Springfield, Massachusetts.  John is a longtime technical consultant to the car clubs, the technical editor for the Rolls-Royce Owner's Club of America, and he’s owned and restored many fine British and German motorcars.  Find him online at www.robisonservice.com or in the real world at 413-785-1665

Reading this article will make you smarter, especially when it comes to car stuff.  So it's good for you.  But don't take that too far - printing and eating it will probably make you sick.