Gibb 68 COPO Nova

[Kurt S]

Originally Posted by William

What I think happened is the transmission plant initially muffed the date coding.
TH400 transmissions were date coded with the model year [68], application [C].
The 396/TH400 Nova was a Spring 1968 launch. When the plant started building the new Nova TH400 transmissions, they incorrectly started the date code sequence as of January 1, 1968, not 1967. Common dates for the Gibb L78 Novas are 68C100 [April 9, 1968] 68C101, 68C102, 68C103, 68C104. Someone noticed and later cars had transmissions coded 68C534 [June 17, 1968].

It's the assembly plant that messed it up, not the trans plant. The Gibb TH400 trans I have seen are stamped correctly, but the POP is in error.

TH400 Code Format: yyaddd
yy = last two digits of the model year
a = transmission application
C = L35 engine
E = L34 engine
X = L78/L72/ZL1 engine
ddd = Julian day of model year
68C493 = Day 127 or May 7, 1968 for L35 Nova / Camaro

SERIAL NUMBER

Ca-69-nnnn e.g. CX-69-3470

where:
C = Chevrolet
X = L78/L72/ZL1 engine
69 = model year
nnnn = 4-digit production sequence number

The new trans were coded 68Y534 with serial # CY-68-10xx, etc.
But what Willow Run put on the POP was the CC trans, which was the L35 trans, ignoring the CY. And despite the 534 day on the trans, they put 103 as the date. So 68C103 on the POP instead of 68Y534. Sometimes the plant used the correct day, but the POP still showed the wrong trans model. All of those POP above should be 68Y5xx.
I can't explain. It wouldn't be for tracking purposes, that was implicit with the new trans code. I noticed this before, but didn't have enough data to see a pattern. Thanks Bill!

Ray - does your car / #37 have the original trans tag?