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Posts in category Decoding

Decoding a GT/CS Tail Light Wiring Loom

One of the rarest, most unique parts on a Ford Mustang GT/CS is the tail light wiring loom harness.  It has a purple tag near the passenger side (right hand side) tail light in the trunk.  This tag has the FoMoCo label and the letters “SXR C8ZX-14405-A”.  Here’s how this part number is decoded:

C8 = 1968
Z = Mustang
X = Ford special or experimental
14405 = Vehicle engineering number

A standard Mustang tail light wire bundle part number is C8ZZ-14405-E or C8ZB-14405-E.  The GT/CS has the “ZX”, which is the code for the special edition Mustang.

Decoding a 1968 Mustang California Special

All GT/CS California Special Mustang VIN’s began with the vehicle identification number prefix “8R01”.

Here’s how the prefix is decoded:

8 = 1968

R =  San Jose, California assembly plant

01 = Designates the Coupe ( hard top) body style.

The next digit in the VIN # is the engine code.  All GT/CS cars could have been equipped with the following engine options:

T = 200 6 cylinder
C = 289 2V
J = 302 4V
X = 390 2V
S = 390 4V premium fuel
R = 428 4VCJ 4 bbl

GT/CS consecutive VIN numbers begin with unit #119,000 and ended with GT/CS and High Country Special (HCS) #172,000.  Most GT/CS’s were produced randomly in the assembly line-up with other Mustangs and Cougars.  The highest concentration of GT/CS production occurred between February 15-20, 1968.  This was primarily due to a massive wholesale dealer event in Los Angeles, California.  By July, 1968, all California Specials and High Country Special production had ended and was phased out.

How to Date Code your Bellhousing

All automatic C3, C4, C6 FMX as well as Ford Top loader 3 speed, 4 speed and peanut 3 speed manual transmission bellhousings are casted with a Ford factory casting number, followed by a date code.

To find the date code, you need to remove the bellhousing from the transmission.  The date code is located on the back side of the bellhousing.  Look for a small circle with a number in it.  For example 64, 65, 66 and so on.  A series of very small bumps appears around the number in a circle.  Each bump numerically represents one month of the year.  A 68 with 4 bumps is decoded April 1968.  11 bumps would be November 1968.

Decoding Tip:  Most cast aluminum engine and transmission parts, as well as brackets, are decoded in this same manner.

Mach 1 or Boss Mustang?

Another viewer question:

Question: Hi, I was reading your write ups on how to decode a Mustang (Mustang Guides). Very nice work. I’m in the market for a ’66-’70 fastback and have a question for you. According to the VIN # what makes a Mach 1 or a Boss a true code car over just a fastback (02 and 05)? Is there a way I can tell if its a real Mach 1 or Boss? Thanks for your help.

Answer:  All 1969 and 1970 regular Fastbacks have a “02” in the VIN #.  A true Mach 1 will have a “05”. A 302 Boss will have an engine code “G”. A Boss 429 will have a “ZZ” in the VIN #.

Does a VIN # indicate a Mach 1?

We received a viewer email and thought it would make for a great blog post.

Question:  I’m kinda new to the world of mustang ownership. I have always loved the 69 Mach 1.  Here is my question:  is there any way to tell a Mach from a regular Fastback by the vin#?

Answer:  Yes, there is a way to tell a 1969 Mach 1 from the VIN#.   The VIN would begin with “905”.  A regular Fastback VIN would begin with a “902”.  “05” is Mach 1 and “02” is Fastback.

If you have a question about Mustangs, let us know.  We’ll post your question (but will keep your name confidential).  Chances are, other people might be wondering the same thing.

Mustang cheers to you!

Date Code Your Timing Chain Cover

1965 Timing Chain Cover

1965 Timing Chain Cover

If you want a numbers matching vehicle, how do you decode a timing chain cover to determine if it’s the best match for your vehicle?  Most timing chain covers have a casting number.  Look on the front of the timing cover to find this number.  In this example, we are using a casting number of C4AE 6059.

“C4AE” =
“C” – 1960’s; “4” – 1964; “AE” – the engineering number used to denote Galaxie (but was also used on many other Fords).

“6059” =
The engineering number code which designates “timing cover”

In addition to the casting number, there will be a small circle with a number in it.  This example has a “65”, which means it was made in 1965.  As you can see, the casting number does not always match the year the part was made.  Within this small circle, there is a series of small dots surrounding the number.  Each dot indicates one month.  In this example, there are 7 dots, which would indicate the 7th month.  The 7th month of a calendar year is July.  Thus, the circle area indicates that this timing cover was made in July, 1965.

Some timing chain covers were service replacements made several years after the casting number.  An example of this would be a C4AE 6059 with a circle containing a “72”.  This would mean that Ford issued a replacement timing chain cover for a vehicle in 1972 (7 years after the vehicle’s production date).

How to decode your 1965-1970 Mustang engine block number

Classic Mustang restorers who are looking to restore a vintage Mustang to concours condition will need to understand how to identify the casting number and date code number on an engine block.  Matching numbers are important to collectors.  The correct casting numbers ensure the Mustang is rebuilt to its original condition and has the correct numbers that would have been assigned at the factory years ago.

This guide is written to help you determine what numbers to look for when accurately restoring your Mustang.  Please remember to indicate below if this guide is helpful to you.

How to decode your 1965-1970 Mustang engine block number

Where to find the engine block numbers:  look toward the back of the engine block on the right hand  side, above the starter. You will find the casting number at this location.

For the purpose of explaining each individual letter and number, we have created asample engine block number and date code.  Then we have broken these numbers down, explaining what each number and letter represent.

Sample engine block number: “C5AE-6015-E   7C20”

C – Designates the decade that the engine block was made.C = 1960’s; D = 1970’s; E = 1980’s and so on

5 – Designates the particular year that the engine block was made.
5 = 1965; 6 = 1966; 7 = 1967; 8 = 1968; 9 = 1969; 0 = 1970

It is important to note:  a more accurate date of when the engine was made is reflected in the date code which follows the casting number.  Casting numbers were sometimes a year or two ahead of the block’s date of manufacture (sometimes they were even behind the date of manufacture).

This is evident, for example, in a 1964 1/2 Mustang with a 289.  The casting number “C5AE-6015-E” and the date code “4D17” show differing years of the engine block’s manufacture date.  One might think that “C5” indicates the engine block was made in 1965.  However, according to the date code, it was actually manufactured in 1964.  Always look to the date code for the correct manufacture date.

A = Designates the vehicle the engine was designed for.
A = Galaxie; D = Falcon; F = made outside the USA; G = Comet; J = Industrial/Marine; M = Mercury; O = Fairlane; P = Autolite or Motorcraft; R = Rotunda; S = Thunderbird; T = Truck; V = Lincoln; Z = Mustang

E = an engineering number used by Ford
(The 289 was originally designed for the Ford Galaxie and the letters AE stayed on the engine block number even after other models were added to the lineup)

6015 = Designates an engineering number used by Ford.
“6015” meant “289 Engine Block”

E = Designates the location that the engine block was made.
Engine blocks were made in Detroit, Michigan and Windsor, Canada
The next set of numbers, “7C20”, indicate the date code.  In this example, even though the casting number reads “C5″, it doesn’t mean that the engine was made in 1965.  You would need to look at this date code to see when it was made, which in this case is 1967.

Breaking the ” 7C20″ date code down:

7 = designates the particular year that the engine block was made  (remember to look at this date code for an accurate reading of the engine block’s manufacture date)
5 = 1965; 6 = 1966; 7 = 1967; 8 = 1968; 9 = 1969; 0 = 1970

C = designates the month that the engine block was made
A = January; B = February; C = March; D = April; E = May; F = June; G = July; H = August; J = September; K = October; L = November; M = December
(the alphabet letter “I” was not used in the sequence)

20 = Designates the day of the month

Deciphering the code:

In summary, the engine block sample number ” C5AE-6015-E    7C20″ tells us the following:

At first glance, one might think that this is a 1965 Galaxie 289 engine block.  However, according to the date code, this engine block is a 289 block made on March 20, 1967.

Ideally, you would want the engine block date code to be 2 – 6 weeks BEFORE your car’s build date.  If you had a car that was built June 1, 1965 and you found an engine block with a date code of 5E10, which is May 10, 1965, this would be a match made in heaven!

Good luck deciphering your dead Mustang scrolls (not to be confused with the “dead sea scrolls”, although I have a few Mustangs that look as if they spent some time on the bottom of the ocean)!

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