Topic: Help: C4 Knowledge needed,

[saa]

I put my hope to you guys 😊 I am missing my C4 transmission for my 1966 mustang convertible, with 289 2V.
The car has assembly date 29M (29Th of December 1965) at San Jose plant, My question are; what is the right code for my car? I know the casting of the transmissions are done 4-6 weeks ahead of the car's assembly date.

Shall the transmission house code be C6AP-, C5AP-, C5DP- or C6DP-?

BR
Stefan

[J_Speegle]

Not sure where you got the 4-6 weeks before the car was finished - guess it was just the standard general ball park answer so often given.

Difficult to find data points since the date and engineering number are not often very visible on the drivers side of the transmission when installed in the car. Many more pictures of transmissions out of the car but most don't have any information of the car they were taken for.

I'll look through what I have maybe some members will have details from their cars to help in the meantime

[saa]

Thanks Jeff,
I understand the date codes (picture attached) and the codes on the transmission tag (attached picture). But the casting numbers are never spoken about. The first year for a Z marked transmission are the 1969 boss 302, so I have hard time finding info for my 1966 convertible built in December 1965.
I hope other readers can contribute with pictures of their 1966 C4 casting numbers.

Best regards
Stefan

From the master part catalog I have following info.
1ST LETTER IS DECADE:
A = 1940'S (OFTEN OMITTED)
B = 1950'S
C = 1960'S
D = 1970'S
E = 1980'S
F = 1990'S

SECOND LETTER SPECIFIC YEAR OF PART: 1-9

THIRD LETTER IS THE CAR MODEL:
A = FORD (GENERIC) / GALAXIE
C = TRUCK
D = FALCON
E = EXPLORER
F = FOREIGN / TRANS AM RACING
G = COMET (LATER MUSTANG)
H = HOLMAN/MOODY HiPo PART
J = INDUSTRIAL
L = N/A
M = MERCURY
N = N/A
O = FAIRLANE (LATER TORINO)
P = AUT0LITE (LATER MOTORCRAFT)
Q = N/A
R = ROTUNDA (GENERIC)
S = THUNDERBIRD
T = TRUCK
U = ECONOLINE/CLUB WAGON VAN
V = LINCOLN
W = COUGAR
Z = MUSTANG

THE FOURTH LETTER IS THE PART TYPE:
A = CHASSIS
B = BODY
D = N/A
E = ENGINE
F = ENGINE ACCESSORIES
J = AUTOLITE
M = HOLMAN MOODY
P = AUTO TRANNY
R = MANUAL TRANNY
S = N/A
U = N/A
W = AXLE
X = MUSCLE CAR PARTS
X = LINCOLN / MERCURY SERVICE PARTS
Z = SERVICE PART

[saa]

Addition: did not get both attachment in the original posting. Attached are the casting dates.

[67gtasanjose]

If you determine a date that is correct, I may have a perfectly good C5 cast, C4 empty case. It shouldn't be too expensive to ship it. My 67 had an earlier case that I swapped internals to a "more correctly" dated case. I also have the internals but those pieces are more or less interchangeable through 1969...excepting the oldest valve bodies (with the PRN2D1).

[J_Speegle]

Addition: did not get both attachment in the original posting. Attached are the casting dates.

Not all use the two circle dating casting

So far I've got a but its not early or late enough to help with your December needs but may help others. As a reminder I can't tie each of the following to a specific car. Just main case information from C4s of the period

C5AP-7006-B Casting date Aug 64
C5AP-7006-B Casting date July 64
C5AP-7006-B Casting date Oct 64
C5AP-7006-B Casting date Mar or May 65
C6DP-7006-B Casting date July 65 from likely a March 66 built car

[saa]

I have checked 2 unrestored original 1966 mustangs for info of engine and transmission casting. Both are San Jose cars.

one Mustang built tag says 17 February 1966, engine assembly date 9 of February 1966, transmission casting date 9 of December and assembled 3 or 8 February (can?t see clear)
The other Mustang built date mars 1966 (can't read date), engine casting date 5M9 (assembled 25 of January 1966), transmission casting date 14 of February 1966.

All transmission starts with C6DP-7006
Big variance, on engines. I assume there where big demands and you simply must take what was available on the shelfs?

Would like to know what other members have as built date on car and casting dates on transmission?

BR//Stefan