I've searched the forum and there are a million threads with VIN questions (especially going back a few years, which I'm guessing was before the VIN decoder on CF existed). But I couldn't find any that quite answered my question: were all the VINs assigned sequentially to cars as they were produced? This would make sense, but the world (and GM) don't always seem to work that way...

When I bought my '96, I was told that it was the 2nd to last C4 off the line and that there was paperwork to prove it. I didn't pony up any extra dough for it being for it (maybe) being the near-last C4, but it would be a pretty neat thing. Unfortunately the "paperwork" turned out to be a carfax report that someone had scrawled "2nd to last 1996" on, with no other reference to how that was determined. So I catch a whiff of BS.

I have read that the last batch of C4s were Arctic White coupes (check), and the door sticker does say it was manufactured in June of 1996 when C4 production ended. So in that sense it's possible. But: the VIN on my car ends in 120521, and according to several sources the production sequence numbers for '96 were from 100001 - 120536 (which I think matches to total 1996 production, less the 1,000 Grand Sports that got their own sequence). That suggests to me that VIN # 120521 was the 16th-to-last C4, not 2nd-to-last. Unless the VINs weren't assigned sequentially, I don't see any wiggle room in that.


The answer doesn't actually matter to me either way, I just wanted the forum wisdom to check my logic.

 

Cars can be pulled off the line and reinserted at a later point in time thus throwing off the sequence of VIN numbers at roll off. Given that your car is only 16 numbers off of the final car I find it hard to believe that your car would have come off and then been reinserted 14 cars later? I’d guesstimate that your car is roughly 2 hours older than the last C4

 

very cool to have one that late and near the end.

 

Thanks ghoastrider, I think so too! It probably has more miles on it now (127K) than a lot of "older" late C4s, but I'm fortunate that POs took very good care of it. She looks like she came off the line a couple years ago.

@OH THREE Z , I didn't realize the line moved that fast back then. Cool info, thanks. (I also think it's doubtful that a car that late got pulled off and reinserted).

 

the vin # and sequence number (or job #) are not the same. In the case of MY 96 the sequence numbers would have been way off in relationship to the vin due to the 1000 grand sports built. In other years during the C4 run there were ZR1s and validation cars that were not meant for retail sale that also would have also caused a difference between the sequence # and vin.

 

This has definitely become an interesting discussion. I'm now more curious about the how'd-they-do-it riddle than when my car was finished. If I've got this right (barkingdogs, I'm going to use your numbers)

Job Sequence Number: Y0274332. The Y makes sense since that's the platform code for Corvette. The rest doesn't intuitively seem to mean anything at first but the DP# gives me some thoughts.
Data Processing Sequence Number: 027443. Seems likely that this is snipped out of the Job Sequence Number, dropping the platform prefix and the "2" suffix. Or maybe vice-versa. It could plausibly be related to the car's place in the generation of orders/builds, since Wikipedia claims there were 39,729 built in '85 - maybe yours was 27,443 / 39,729. Maybe the "-2" indicates a coupe or convertible...in the VIN, "2" is a coupe and "3" is a convertible. I wonder if there might be a different digit in that position for Grand Sports, too?
VIN, with Production Sequence Number embedded in the last 6: xxxxxxxxxxx126553. Seems completely unrelated to the Job Sequence and Data Processing numbers.

I agree with you, barkingdogs, that the Job/DP number <-> VIN sequence isn't correlated. So, here's my WAG: When the car is ordered, a job sequence number is generated with the platform code followed by a sequential number based on orders for that model, with a suffix for body style or paint or something. Whatever the Data Processing Sequence Number is used for, it gets derived from that. Eventually a bunch of orders get batched together and re-sorted at the plant for ease of assembly - whether it be by paint color, body style, or whatever other options might make a difference - and that's when the VINs are generated and assigned.

As a hypothetical, let's say your car got ordered the same day as nine others.

1) Y-027440-2 <white>
2) Y-027441-2 <red>
3) Y-027442-3 <black>
4) Y-027443-2 <black>
5) Y-027444-2 <blue>
6) Y-027445-3 <white>
7) Y-027446-3 <white>
8) Y-027447-2 <black>
9) Y-027448-2 <black>
10) Y-027449-2 <yellow>

Then they get shuffled around for manufacturing needs and you get a different sequence, to which the VINs get assigned with sequential "last 6s".

x) Y-027412-2 ---> xxxxxxxxxxx126550
x) Y-027417-2 ---> xxxxxxxxxxx126551
x) Y-027442-3 ---> xxxxxxxxxxx126552
x) Y-027443-2 ---> xxxxxxxxxxx126553
x) Y-027447-2 ---> xxxxxxxxxxx126554
x) Y-027448-2 ---> xxxxxxxxxxx126555

It seems possible, then, that the VINs (with the embedded Production Sequence #) indicate the order they were built even if the other identifying numbers are haphazard. What we need are some other people's Job Sequence, Data Processing, and Production Sequence numbers to test the theory. I don't have my build sheet, so I'm no good. (Even better would be somebody who's lived through this stuff and just, y'know, knows how it worked).

And yes, I've now officially put too much thought into this. A rare slow day at work!

 

Also, this has been posted elsewhere on the forum but I tripped over it trying to search for production time.
There's a bit on the BG plant that starts around 7:45 and in all the shots where there are a bunch of cars moving along the line, it looks like there is indeed a bunch of the same color all in a row.