1979 Differential Decoding

[Robert C.]

1979 Corvette.

Looks like OH 2 36 W 9 E 1

OH = 3:55
2 = ?? (plant code??)
36 = MARCH 6th

---- or 236 Julian which is Sept 3., 1979 ----this is a August build car

W = Warren
9 =
E = Eaton
1 = first shift

[Tom R.]

Re: 1979 Differential Decoding

1979 Corvette.

Looks like OH 2 36 W 9 E 1

---- or 236 Julian which is Sept 3., 1979 ----this is a August build car

Yeah...its not pretty (stamping) even the E looks like a B but during C3, three different formats were used to code differentials. I've got a photo of my 78 that used the same format as your 79 but couldn't readily find it. The plant code would be the "W."

Is it possible it was changed out?

[Robert C.]

Re: 1979 Differential Decoding

Well, based on the mileage and the original shocks in the back, I don't think so......

"Corvette by the Numbers" noted 7 digit codes for the C3's, couple years
had 8 digit.......this is 9.

If you happen to find your picture, it would be nice to compare 'em

Thanks for your help.

Bob

[Michael D.]

Re: 1979 Differential Decoding

...or 236 Julian which is Sept 3., 1979 ----this is a August build car...

I'm not certain we have decoded it correctly. You can't have a car assembled in August with a differential dated September.

[Tom R.]

Re: 1979 Differential Decoding

I'm not certain we have decoded it correctly. You can't have a car assembled in August with a differential dated September.

We've arrived at that conclusion...we are working to determine the correct format.

[Robert C.]

Re: 1979 Differential Decoding

Part of the question is if the "2 36" is a julian date (e.g. 236 day of 1979)
or this is a "2" and "36".

Is the "2" a plant code and "36" indicate March 6th???

Chevy by the Numbers says Julian dates, but the spacing I think would be
all together, versus the gap.

Hence, my questions.

Bob

[John H.]

Re: 1979 Differential Decoding

Chevy by the Numbers says Julian dates, but the spacing I think would be
all together, versus the gap.

Bob -

Those characters weren't stamped with a gang holder (like the engine pad stamp was); the diff code was stamped with individual character dies and a hammer, so you're likely to see all manner of odd spacings.

[Tom R.]

Re: 1979 Differential Decoding

Those characters weren't stamped with a gang holder (like the engine pad stamp was); the diff code was stamped with individual character dies and a hammer, so you're likely to see all manner of odd spacings.

And so here is my 78. This is a November 10th (C10) build date with a 311, and 7 (1977) Julian date code for the rear axle. You see the similar lack of consistency with the stamping. Broadcast code is OK

Rearaxlecode_78.jpg

[Tom R.]

Re: 1979 Differential Decoding

Part of the question is if the "2 36" is a julian date (e.g. 236 day of 1979)
or this is a "2" and "36".

Is the "2" a plant code and "36" indicate March 6th???

Chevy by the Numbers says Julian dates, but the spacing I think would be
all together, versus the gap.

I've written and published in Restorer articles that late model C3s production methods are "perceived" to be the same as early C3...yet they were not and this is a typical example published in "Corvette by the numbers."

It states on page 458-59 "the third digit is the plant code." Well as we've seen on a 78 and 79, it is actually the 6th digit. Even its example is incorrect (OH C 218 1). That's why I wrote previously that three different code configurations were used from 1968-82.

So the interpretation of the code is correct...the question remains why is a September 1979 axle on an August 1979 Corvette.

PS...also nice to have a comprehensive "Corvette" reference collection.

[Robert C.]

Re: 1979 Differential Decoding

Thanks Tom, very interesting.

Maybe this was replaced at some point. Build sheet was dust and I couldn't make anything out (seeing if this had the optional rear axle ratio)

BTW, I have the Restorer on DVD and would like to read your article.

I searched on your name and didn't find it. Clue me in, I'd like to read it !

Thanks for your help

bob

[Robert C.]

Re: 1979 Differential Decoding

My goof.

Julian 236 would be Aug 24th, 1979.

The Built date is August 28th, so this would be correct.

Bob

[Robert C.]

Re: 1979 Differential Decoding

236 would be August 24th, 1979.

Build date is August 28th. My mistake with the julian date

[Tom R.]

Re: 1979 Differential Decoding

236 would be August 24th, 1979.

Build date is August 28th. My mistake with the julian date

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