I have a question for Joe P. regarding dated parts on items in our Oldsmobiles. You have indicated in the past that these parts are nearly always (or always?) within 3 months of the car build date. This seems to differ a bit from what the Corvette (I know, plastic pigs, but they are GM, too!) experts indicate for their cars. They allow up to 6 months before the car build date on dated items in judged events, with a special allowance of up to a year for glass (and horns, too, as I recall). One thing I noticed in the restoration of my '68 442 was that the block is dated "304", or about November 1, 1967, but the car build date is 04A, or the first week in April 1968, which is a full 5 months later. I am 99.99% sure the block is original as the car has been in our family since February 1969. The block has the correct VIN derivative. Other oddities I discovered during restoration included the posi unit (had a date of "187" which is early July 1967 and even outside of the 6 month window), and the ring gear (dated "339" which is early December 1967; pinion gear was dated "73"). The rear end has never been disassembled since the car has been in our family. Everything else checked out to within 3 months of the build date of the car. But it does strike me that sometimes there are items that fall out of the 3 month window. Maybe I'm just digging too deep in the weeds here, but I would like to see your thoughts on date-coded items and, in particular, the items that fall outside of the 3 month window. Thank you! Randy C.

 

(Both Randy and Joe will know I'm ribbing them here, but.....)
Hey, there are some people here other than Joe that know a thing or two!

A little logic goes a long way here. And this whole "correct date code" thing is a generalization anyway. 3 months is a generalization based on what what has been observed over the years. There are all kinds of things that happen at the factory that can effect alterations to general practices.
Chebbys could very well be different as a whole. I can think of 3 factors that would easily widen the 3 month window.
1. Higher production can spread out production.
2. How common the part is, interchange, etc.
3. When in the model year could also affect the window as would the how far the part is in its life (is it new for the year, or in its 3 year of production.
I would expect Oldsmobiles to more hand to mouth in production than Chebbys.
Since "matching" date codes is so general, and there are so many factors that can alter the dates made, it becomes somewhat a tail chasing affair.
Randy, you know I share your thirst for these details and likewise look into the dates to try to determine if parts are original to a car.
Where I think things "go too far" (for me at least) is when someone feels the need to find not only a correct part, but a "correctly date coded" part. To me a the date code is rather meaningless at that point, as it a replacement. What's next, date coded repops? (Yes, I know its already being done).

 

I'm shocked, SHOCKED I tell you, that you would say that! ()

Maybe, but let's not forget that there was a time that the Cutlass Supreme was the number one selling nameplate in the country and Olds actually made it to fourth at one point in annual sales. Of course, then GM started putting Chebby motors in Oldsmobiles and it was downhill from there.

Amen! At some point, this level of detail goes from being a hobby to being work...

Besides, when you go that far, you can't drive the car anyway, so why bother. It's just become art at that point.