Quote:
Originally Posted by c10sport
Say Keith Seymour, I have a plant question. I am running the 454SS registry (yes, in addition to my SPID project, I have WAY too much free time) and there's a guy claiming to have the second 454SS built. However, his VIN says otherwise, the last 6 digits of the VIN for the second 454SS I have in my database is 139514, his truck is 156538.
So did the plants randomly pluck trucks off the line and give them a higher VIN sequence than the trucks before and after it?
I know the answer, I am just wondering what your thoughts are.
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“Randomly pluck” is kind of an improper visual, so let’s review a bit and then I’ll give my opinion:
Vehicle orders come into the plant and are tracked by the “Dealer order number”. Once the order is approved and the build is scheduled it is assigned either a Carrier Sequence Number (CSN) or Primary Vehicle Identifier (PVI). One of these numbers will be used to track the vehicle through the body shop build and through paint. Once the vehicle is ready to drop from paint into Trim both the VIN and the General Assembly (GA) sequence number are established. The GA sequence number is the gold standard for tracking the build within the assembly plant; the VIN is never mentioned other than to make sure the correct one is installed on that GA sequence number, just like a tune up label or Mulroney window sticker or SPID label. Nobody in the vehicle assembly plant really cares about the VIN (unless it gets messed up).
Having said that the vehicles drop down roughly in VIN sequence, but with the following caveats:
a) Different nameplates can have different VIN sequence starting points, so Chevys increment in one “family” but GMCs or Cadillacs (or Pontiac or Oldsmobile) are incrementing up in a separate cadence.
b) Vehicles can be held up after the VIN is established, for example if the vehicle needs some type of extended off line repair or if downstream workload level is affected (ie, too many manual trans in a row, too many sunroofs in a row, etc). This can be done either via a shunt spur which allows the vehicle to circle/stop in a repair area, or can be as serious as removing the body with a forklift for later reinsertion (in the most dire circumstances).
The chassis with it's assorted major components (frame, engine trans) are started at this time. Keep in mind these will also have to be coordinated with the same GA sequence vehicle being stamped with the same VIN as the body making its way though the other half of the process. Nothing random or spontaneous happens here, because there is too much risk at stake with repect to getting any one of these converging body/chassis builds out of sequence.
I’ve attached a chart below with fictional data in an attempt to highlight this. So you can see it might be impossible to confirm that vehicle 123456 came immediately before vehicle 123457 (unless you were there), but we can usually pretty safely say that vehicle 123456 came before vehicle 125678.
However, what I have described above is true only within a specific plant. Each plant is doing this and incrementing up at its own pace, with no linkage to any other plant, based on line rate, overtime, work stoppages, downtime, etc. So there is no way to compare the VIN build date from any one plant to another (unless you have the actual build date in your database).
So – my interpretation:
If both vehicles were built within the same plant – you are probably right (139514 very likely came before 156538), since you are dealing with the same nameplate (Chevrolet) and therefore are within the same VIN sequence starting point (probably 100001).
If the two vehicles are from different plants – there’s probably no way to know (day wise) which was completed first, at least not without a lot more digging.
K