How to decode your Jeep CJ firewall tag

What is the significance of a Jeep CJ’s firewall tag?

The firewall VIN tag — referred to as the “vehicle identification plate in Jeep manuals — is a small metal identification plate mounted to the engine-side of the firewall on many Jeep CJs. While it’s often overshadowed by the dash VIN, this tag plays an important supporting role in documenting your Jeep’s original identity.

For CJ enthusiasts, the firewall tag is valuable because it typically includes the VIN (or a serial number tied to it) along with factory details such as the model, engine, transmission, axle ratios, and original paint and trim codes. This makes it a key reference when restoring a CJ to period-correct specs or verifying how it left the factory.

Because firewall tags are attached to the body (instead of the fram) they’re sometimes lost during engine swaps, repaints, or firewall repairs. When present and original, however, the firewall VIN tag adds another layer of authenticity and helps tell a more complete story of your Jeep’s build history..

Where is the firewall tag on most CJs?

Although many have rusted away or rotted off, the firewall tag on Jeep CJs was usually on the driver side, about halfway down the engine side of the firewall. The tags measured approximately 2” by 4”.

How do I replace my rotted, rusted, or otherwise illegible firewall tag?

When I purchased a repli-tub from Willys-Overland, I wanted to afix my original firewall tag to it. Unfortunately, the original tag was rusted to the point of being about 80% unreadable. So, I decided to recreate the firewall tag — relying on my validated knowledge of the Jeep’s OEM configuration.

I found this eBay seller who will custom generate a firewall tag for you. The craftmanship was on point and signalled authenticity.

How do I decode my firewall tag?

Like decoding a VIN, decoding a firewall tag requires you to know the year of your vehicle (which can be gleaned from the firewall tag itself). This is because the structure and contents of the tag varied by year.

1981 - 1986

The introductory sections to Jeep service manuals and parts catalogs usually presented a firewall tag “decoder.” The following decoder is from the 1982 technical service manual, and it applied to all CJs from 1981 through 1986.

The tag sections are as follows:

  • Sales Order No.: Abbreviated as “SON,” this is an internal-to-AMC tracking number. It does not identify the vehicle to the public the way the VIN does, but it can approximate how and when a Jeep was built.

  • Special Sales Request and Order Number: Abbreviated as “SSR & O No.,” this number is for “Jeep vehicles [that] are built to special order with other than standard parts or equipment.” The number was meant to “assist the dealer in ordering correct replacement parts.”

  • *: This is, according to the technical service manual, “for factory use only” — one should “disregard.”

  • Paint Option Number: We maintain a list of paint option numbers, which varies by year.

  • Trim Option Number: TBD

  • VIN: We discuss the components of the VIN and how to decode it.

  • Jeep Model No.: TBD