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[email protected] 07-14-2014 09:33 AM

How rare is my 1966 Mustang GT Fastback?
Would appreciate any constructive, fact-based insights into my logic (or lack there of) below….thanks!

Using three (3) Ford Mustang registries, the 1966 and 1967 national production data and some additional book/magazine article sources, I am attempting to determine the uniqueness of my 1966 Raven Black exterior (Dark Red w/Red interior) Mustang GT Fastback…build date (03B) February 3rd, 1966.

Here goes…. of the 607,568 1966 Mustangs built, 35,698 were Fastbacks and 27,809 (4.6%) built were 2dr fastback cars with STANDARD interiors (63A). 
Mine is a verified GT, with an A-code engine (Challenger Special), a 4-speed top-loader manual transmission and is Raven Black exterior with Dark Red w/Red interior.

As a baseline and relative comparator set of data….the 1967 National Production #s indicate that there were 71,042 or 15.01% Fastbacks manufactured out of 472,171 total Mustangs produced; and 5.3% of the overall production of Mustangs (472,171) were GTs which equates to 25,098 GTs. Additionally, Kevin Marti ‘s book indicates that approximately 64.6% or 16,213 of the 1967 GT’s were Fastbacks. But we also know based on the 1967 National Production #s that only 22.8% (16,213/71042) of all Fastbacks were GTs. In an article by Jerry Heasley
from the
April 1995 Mustang Monthly Magazine, he wrote….”although we have no breakdowns by body style, in our experience, the fastback was the most common GT, followed by the convertible and, finally, the hardtop.”…that aligns with Marti's 64.6%.

The 1966 National Production #s indicate that there were 35,698 or 5.88% Fastbacks manufactured out of 607,568 total Mustangs produced; and according to Jim Smart's book, 1965-1990 Mustang GT/Mach 1 Guide, 1966 GT production, was 25,517 or 4.2% of total production. So, significantly fewer (about half as many) Fastbacks were produced in 1966 as compared to 1967 but slightly more GTs were manufactured in 1966. The 1966 GTs were a smaller percentage of the overall production of Mustangs which was so much higher in 1966 (607,568) as compared to 1967 (472,121).

So, let’s assume that a similar percentage (23%, 1st unknown #?) of the 35,698 Fastbacks built in 1966 were GTs. That means 8,211 Fastback were GTs. Of those 8,211 I’m guessing that 75% (or 6,158) (2nd unknown #?) of the 63B (luxury interior) Fastbacks were GTs, which means that there were 25% or 2,053 63A (standard interior) Fastback GTs. But then that only equates to 32.2% of the overall GTs being Fastbacks, which seems correct to me given the fact that again, half as many Fastbacks were produced in 1966 as compared to 1967

We don’t know how many 1966 mustangs were manufactured with A-code engines but according to CJ Pony Parts, we do know that all GTs had 4-barrel carburetors so all GTs were either K code or A-code engines. Also, according to, the very basic rule is that every GT must be an "K" code car or an "A" code car built after mid February 1965, no exceptions. Mine is not a K-code unfortunately….but it is an A-code….engine build date (6A20L), January 20th, 1966.

A little further on the K and A code engines (as it may help someone else reading this). We also have an idea of the percentage of K-code mustangs produced in 1966. I’ve seen two #s: either 5,469 or based on the Mustang Production Guide and internet blogs: 1.5% of 607,568 cars or 9,114….I’ll use the more circulated and accepted number of 5,469. A high percentage of K-code engines went to the GT350s (2,377) and 95% of the reminder (5,469-2,377=3,092 * .95 = 2,937) K-codes went to other GT production (25,517-2,937 = 22,580). A K-code engine could be purchased for a non-GT equipment package but there were very few. So, the ratio of K-code engines to remaining GT production is 12.5%, which means that the remaining GTs (22,580 or 88.5%) had A-code engines. That number of A-code engines (22,580) more than covers the number needed to meet the necessary amount of A-code engines needed for the 2,053 63A (standard interior) Fastback GTs calculated above.

According to, approximately 50% of 1966 mustangs had automatic transmissions. According to CJ Pony Parts, 1966 GTs could have either an automatic or manual transmission. According to, most cars in 1966 were ordered or equipped with the Cruise-O-Matic transmission. The second most ordered transmission was the standard 3-speed manual, which was standard for both the 200hp (C-code) and 225hp (A-code) engines. The rarest transmissions ordered in 1966 were 4-speed manual transmissions….that’s mine! According to two of the Mustang registries, about 14.5% of the mustangs registered had 4-speed top loader manual transmissions (14.39% and 14.52%). It would be safe to assume that a higher percentage of GT Fastbacks were 4-speed manual. Based on the information available, I am going to use 17.5% (3rd unknown #), which would mean that there were approximately 359 standard interior GT Fastbacks, with A-code engines with 4-speed top-loader manual transmissions.

In 1966 there were approximately 25 paint colors to choose from with Candyapple red, white and various shades of blue dominating the exterior colors with close to 50% of mustangs’ exterior color being one of those three colors. My car’s original exterior (according to the door tag) and its current color is raven black (code A). According to the statistics gathered by Jim Smart and Jim Haskell in their research for the Mustang Production Guide (pulled from Vintage Mustang Forum), the colors below were used on 1966 Mustangs; the use of Raven Black paint was declining from 1964 ½ @8.3%, 1965 @ 5.8% and 1966 @ 3.8%:

1. Candyapple Red, code T, 13.8%
2. Wimbledon White, code M, 12.5%
3. Ivy Green, code R, 7.9%
4. Springtime Yellow, code 8, 7.8%
5. Nightmist Blue, code K, 7.6%
6. Silver Blue, code Y, 7.2%
7. Vintage Burgundy, code X, 5.7%
8. Sauterne Gold, code Z, 5.7%
9. Emberglo, code V, 5.6%
10. Tahoe Turquoise, code U, 5.5%
11. Raven Black, code A, 3.8%
12. Arcadian Blue, code F, 3.6%
13. Silver Frost, code 4, 3.4%
14. Signalflare Red, code 5, 2.6%
15. Antique Bronze, code P, 2.4%
16. Sahara Beige, code H, 1.9%

The data above are verified using the 3 registries (registries = 4.89%, 4.81% and 3.90%); Smart and Haskell’s 3.8% Raven Black paint makes sense, so that’s only 14 standard interior GT Fastbacks with A-code engines, top-loader 4-speed manual transmission with raven black exterior paint.

Most of the raven black cars had either red or black interiors (80%)…so 14 x.80 = 11 with red or black interiors. Overall the interior trim “25” (Red Crinkle Vinyl and Red Rosette Vinyl) makes up about 7.1% of the registry, while black interior cars make up about 33.40% of the registry cars. Black was a more popular interior color than red by about 4 to 1 so I’m going to use 25% (4th unknown #) as my red interior number. So, of the 50 standard interior GT Fastbacks with A-code engines, top-loader 4-speed manual transmission with raven black exterior paint, with either black or red interior, 3 (14 x 25%) had dark red w/red interior.

So, that's the number I've come up with using the logic above…..3. Assuming that is not correct but maybe a ballpark? I know that there isn't much data pre-1967 but would appreciate any of your comments or insights…thanks.

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