Mopower Garage

Published by Christopher J. Holley | Mopar History & Tech | October 2025

For Mopar enthusiasts, few discoveries are as thrilling as unfolding that fragile, yellowed piece of paper tucked beneath a seat cushion or hidden behind a door panel. It is the broadcast sheet, Chrysler’s factory build record, and it is the single most important document for decoding what your car really is.

During the muscle car years, every Plymouth, Dodge, and Chrysler rolling down the assembly line carried its own broadcast sheet. It was not meant for owners or collectors; it was an internal roadmap for line workers, telling them exactly how to build that specific car. Each box, number, and code ensured the right parts landed in the right places at the right time. Decades later, these once-disposable sheets have become priceless time capsules.

The Birth Certificate

Across the top rows, the sheet lists your car’s vital statistics: the VIN, scheduled production date, and assembly plant, Hamtramck, St. Louis, Lynch Road, or Los Angeles. This section confirms when and where your Mopar was born and ties it to its fender tag and dash VIN. For restorers and collectors, that is ground zero for verifying authenticity.

Heart and Muscle

Next comes the fun part, the powertrain data. Here is where you learn whether your car left the factory with a 383, a 440 Six-Pack, or the mighty 426 Hemi. The transmission code tells whether it ran a Torqueflite or a pistol-grip four-speed, and axle data reveals whether it came with a Sure Grip rear and what gear ratio it carried. This section defines the car’s personality and its performance pedigree.

Paint, Trim, and Attitude

A Mopar’s look was every bit as bold as its horsepower. The broadcast sheet documents the original paint code, stripe package, vinyl top, and even the type of wheel and tire it wore. Inside, it calls out seat style, interior color, dash setup, and options like a tachometer or console. If you are restoring a car, this is the blueprint for getting the details correct, right down to the carpet color and radio type.

The Hidden Hardware

Buried deeper in the grid are codes for suspension, brakes, and tires, details that separate a boulevard cruiser from a street brawler. HD torsion bars, front disc brakes, and Goodyear Wide Treads often meant the car was destined for serious work. These clues help you determine whether your car was built for performance, luxury, or something in between.

Options and Oddities

Every extra, power steering, air conditioning, lighting packages, even trunk mats, shows up somewhere on that sheet. Chrysler’s option coding was notoriously complex, but once decoded, it tells you exactly how the car was equipped when it rolled out the door. Matching these codes against the fender tag or parts catalogs is how experts prove a car’s originality.

Proof of Life

Down at the bottom you will often see punch marks or initials, signatures of factory inspectors and routing clerks. Those tiny notations meant your car passed final inspection and was cleared for shipping to the dealer. It is a small detail, but to collectors, it is living proof that this exact machine once moved down that assembly line.

Why It Matters

Unlike GM or Ford, Chrysler did not keep master build records. That makes the broadcast sheet the only surviving document that tells how a specific car was born. It is a window into the past and, for many cars, the key to verifying originality and value. Finding one intact is like unearthing buried treasure, it is the DNA record that separates the real deal from the clone.

So, next time you are pulling a seat or peeling back carpet on a restoration, keep an eye out for a brittle, blue-printed relic from 50 years ago. If you are lucky enough to find one, handle it like gold, because in the Mopar world, it is.