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?

[copo-2]

I have an old polaroid picture that I looked back upon when taken while very new. In searching for any evidence of Fred Gibb's association, I thought it might have had the window sticker that might have still been there? I didn't find any nor can I remember one being there when driving it away from DHPC. I do remember hauling the air pump home in the trunk pulled because of the optional headers. Still nothing pointing toward Fred Gibb? At this point no reason to really look for anything other that what was already known? While putting the car back together, the need to freshen the original motor became an issue. Knowing that our engine builder was still in the former DHPC building doing competition work as he had done for DH before, it was taken back for him to refresh. Speaking with him and exchanging some DH documents, He mentioned that I should look into the car that the engine came from, that additional interesting information about documenting of the Nova was there to be found? Curiosity of what he had mentioned was beyond my understanding? The question was, where to start the search? He would not comment any further but his comment was the start for my looking for any information I could find?

Kurt S In answer to your question in the above thread, yes I do have the original tag and quite a bit of other transmission documentation that I would like to post later together. Thanks for the interest!