The Mustang pictured below (bottom) was first purchased by my father-in-law, Buddy, in 1986, in Connecticut. Shortly after, he purchased a second six-cylinder convertible and sold the pictured one to my wife's cousin, Ronnie. Dad died in 1994. When Ronnie decided to sell the car to finance an in-ground swimming pool in 2006, my wife Sharon and I decided to buy it, and brought it home to Tennessee.
The car had undergone a cosmetic restoration before Dad bought it, and apart from some minor detailing since then, was still in the same condition when we bought it.
In June 2010, I found out it was a Sprint 200, Package A, 3-speed manual transmission. And after reading an article in the archives of the Mustang Times by Jim Smart, went looking for the Broadcast (Build) Sheet. I found it wrapped around the wiring harness behind the speedometer. After a brief search to find out what all the codes meant, I realized that surprisingly little is known or published about these documents. So I decided I'd try to attempt to decode it myself. This blog is a journal of that research.
All discussions below currently pertain to only 1966 Mustangs.

Tuesday, December 28, 2010


The last box on the top line is the DSO/FSO/PTO.

DSO has a dual meaning on a door data plate or build sheet. When the code is two digits long, it indicates the District Sales Office for which the order was intended. When a dealership ordered a car, they didn’t contact Ford directly. They went through their District Sales Office. For instance, a dealer in Bradford, PA with a dealer number of 37J551 on January 16, 1966 would have had a home office of Buffalo, New York (District #37).

If a car was to be built with non-standard production features, a six-digit code was stamped on the door tag. The first two digits still indicated the District Sales Office responsible for the order. The last four digits were a Special Order Number to keep track of the order and were indicated in the DSO/FSO/PTO line of the build sheet.

According to Kevin Marti, there were four types of special orders:
  • ·         DSO - Domestic Special Order, which included Shelbys and Boss 429’s
  • ·         FSO - Foreign Special Orders
  • ·         PTO - Paint & Tire Orders, which included special paint and special tire usage
  • ·         SPO - Special Production Orders
For instance, if a dealer special-ordered five Mustangs for a promotion in a non-stock paint color, such as a Thunderbird Sapphire Blue, all five Mustangs would have the same six digit DSO code, ie. 24-0327, with 24 being the ordering sales office (Jacksonville, FL), and 0327 being the Special Order Number (sequential).

Below is a punchcard obtained from Charles Turner, with the areas in yellow indicating the location of the Special Order Number as it was first assigned by Ford. If the car had no unusual features, these areas were normally blank, as in the case of Charles’ punchcard. Below that is an export build sheet with a four-digit FSO.

Saturday, December 25, 2010


The 5th box from the right carries the code for Convertible Tops.

CONV TOPS (Convertible Tops)
Black, Manual, Plastic Glass
Black, Power, Plastic Glass
White Manual, Plastic Glass
White, Power, Plastic Glass

Sunday, December 19, 2010


The 4th box from the right on the bottom line is titled:

I have come to believe that RT DRIVE stands for right-hand drive, LS LAMPS stands for left side headlamps, OMIT SL. BM stands for omit sealed beams, and TROP BATT stands for tropical battery. I may revise this in the future, but this is my present understanding. 

I have a build sheet on file for an export car with a code in this box of 5. Most build sheets have no code in this category; including two other export cars I have on file. The build sheet also has a special note on the bottom: Use 22:1 Steering Ratio - Part C4ZR-3504-E; and front and rear springs, and shock codes are unlike any I've seen on other '66 cars.

At first I thought this unusual, and that it might indicate a right-hand steering box. My previous information was that Mustangs used 22:1 standard steering and 16:1 for power steering and the Special Handling Package. If 22:1 was a standard steering box, why specify it at the bottom of the build sheet - unless there was something else unusual about it? Right-hand drive? I have since found out that 19.9:1 was the ratio for the standard steering box. I have no clue why they changed it for this car.

I attempted to do a little detective work with the aid of my two friends Veronica Sczbecki and Jeff Speegle.
The car’s build sheet contained a DSO code of 95 02 84. There are six other Metuchen cars in Smart's Mustang Production Guide with the same DSO of 950284; all of them with owners in Sweden. All are A-codes. 3 are fastbacks and 3 are coupes. All were built on October 8th the same as this one. If we look at the VIN’s in question here, we start with one ending in 318 and conclude with one ending with 491; so a potential of about 173 cars in the order. Maybe there was a clue to be found in its country of delivery.

Sweden had legal left-hand traffic (USA has right-hand traffic) from approximately 1734, well into the 20th century, despite the fact that virtually all the cars on the road in Sweden were LHD. (One argument for this was that it was necessary to keep an eye on the edge of the road, something that was important on the narrow roads in use at the time). Also, Sweden's neighbors Norway and Finland already drove on the right, leading to confusion at border crossings. This not withstanding a right-hand drive car was not “illegal”, and in some cases might have been “more natural” in a left-hand traffic environment like Britain’s.

In 1963 the Swedish parliament passed legislation ordering the switch to right-hand traffic. The changeover took place at 5am on Sunday, 3 September 1967, well after the 1966 Mustang model year.

Veronica pointed me to some internet sites that talked about right-hand drive cars in Australia. (48) 1965 and (161) 1966 Mustangs were converted to Australian specs (including right-hand drive) by Ford of Australia at their Homebush facility. It’s believed that this was done by a subcontractor. These cars were apparently shipped from one of the U.S. plants (likely Metuchen), either as pre-assembled vehicles or as "knock-down" units. This is the only record of a “Ford” produced right-hand drive Mustang. Some other Ford vehicles were known to have been assembled as right-hand drives; the Cortina for one. It may be possible that the build sheet was composed to be utilized in those instances as well. See: for further info.

“Think it’s a long stretch [right-hand drive] with a number in a box and at least four different possibilities. Given it was likely ordered for Sweden I think it’s highly more likely that the 5 represents a change in the lights since that is something we see often (as a higher requirement) on European delivered Mustangs.
The omit seal beams is odd as I'm not sure where (country) or why sealed beam headlights (if that is what SL Beams is referring to) would be illegal in any specific country in 66 unless these same build sheets were also made for use in other countries were Fords were built that year - a possibility IMHO.”
– Jeff Speegle

Jeff’s statement above prompted me to do a little more research:
 Most low-beam headlamps produce an asymmetrical beam focused for use on only one side of the road. Headlamps for use in LH-traffic countries have low-beam headlamps that throw most of their light forward-leftward, while limiting the light range forward-rightward; the beam is distributed with a downward/leftward bias. Headlamps for RH-traffic countries (USA) have low-beam headlamps that throw most of their light forward-rightward, while limiting the light range forward-leftward; the beam is distributed with a downward/rightward bias. (see photo below) The beam thus lets the driver see obstacles and road signs on his side of the road at a safe distance, without blinding oncoming traffic. The LS LAMP in this build sheet category might refer to the readjustment of the headlight beams to the left side. This would have been necessary for Sweden’s left-hand traffic pattern at the time that the Mustangs were delivered. When the traffic pattern in Sweden changed in 1967 to duplicate that of the USA’s, it likely meant that Swedish headlights had to be re-adjusted.

My present conclusion is that the 5 code we see in this box means that the headlights were adjusted for a left-hand traffic pattern. I currently have no other codes in this category pertaining to Mustangs, or other Ford vehicles.
RH Traffic Headlamps


My decoding process has slowed down considerably as I begin to encounter the more difficult and obscure codes.

This post deals with the Radio Noise Suppressor - Transistorized Regulator - Alternator codes found in the 3rd box from the left on the second line.

The Radio Noise Suppressor is normally found by the voltage regulator - a little round can that looks similar to the condenser in a distributor (pictures below). In 1965 there was also one located at the alternator. The 1966 alternators built-in this feature. In essence, there are two of them. Their purpose was to reduce radio interference from the electrical system. Despite the fact that Ford had a code for these, and that all radio equipped cars would come with them, the build sheets I have on file don't use the Radio NS code. I suppose the presence of the radio itself was sufficient indication for line workers to install the suppressor.

 The only code I've seen in this box for Mustangs is 8 for the 42 AMP alternator. I'm finding this on all 1966 K-code cars.

I've attached below a description of the Alternators used for '66

55 AMP (Ford)
55 AMP & Regulator
53 AMP (Leece – Neville)
53 AMP & Regulator
60 AMP (Leece – Neville)
60 AMP & Regulator
Radio Noise Suppression
Noise Suppression & Regulator
55 AMP & Noise Suppression
Suppression – Regulator – 55 Amp
53 AMP & Noise Suppression
Suppression – Regulator – 53 Amp
60 AMP & Noise Suppression
Suppression – Regulator – 60 Amp
Transistorized Regulator