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VINs and assembly line
Sorry but I have spent much time and miles trying to learn a lot about our cars - especially about production of our cars.  The following is intended to be educational and informative.  If anyone disagrees with my current understandings on this - please post to help us all learn.  THX Ray

Numbers associated to the VINs are not sequential in line for production.  While close numerically associated VINs usually occupy a similar timeframe, one car with a VIN numerically one away from another rarely would indicate "next in line" on the production floor assembly line.  And some of the numbers were created (used) then never built as an order got cancelled for whatever reasons. Those numbers just are used but never actually made into a car...  So a car's VIN that is (any number)  away from another does not indicate anything other than the lower numeric one was MAYBE built before one with a higher numerically given VIN.  Of course the more the 2 VINs differ, the more likely this is to be true.  From my experience, the best determination as to what cars might have shared the line would be the actual build date and definitely not the VIN.  And even this build date might not be the greatest where a car was not completed on the line and 'held back' or 'to the side' for some reason ; like ran out of ___ so awaiting delivery of part(s).  It (production) is a little more complex than a first glance indicates!!!!


1971 Boss 351  
1972 Q code 4 speed convertible 
1971 Mustang Sportsroof  351-2V FMX 
1973 Mach 1 (parts car)

I like you enjoy researching the history of our cars, how they were built and more specifically researching my car's history. As we know Cougars were also built on the same Dearborn assembly line and were sequenced and bucked along with Mustangs, which just adds to the challenge and mystery behind the production numbers. I would add that the more accurate way of determining when a car was built and sequence, is the rotation or item number on the buildsheet. My interest is mostly focused on 1973 Mustang convertibles, so many years ago I corresponded with the late great Lois Eminger, who was well known in our hobby for having rescued from the trash heap and preserving many years of original Mustang invoices. Before Kevin Marti bought what remained of the invoices from her estate, with proof of ownership, you could purchase the invoice for your car for $ 35.00.

Anyway, I thought all might find this letter from Lois in 1996 regarding the last build 1973 convertible and the last 1973 Mustang VIN#. She also speaks to how our cars were sequenced on the line.

[Image: loisrspx.jpg]

1973 H Code Convertible - Medium Copper Metallic - June 8, 1973, Built Ford Marketing Sales Vehicle
[Image: DSC_0266xsm.jpg]
[Image: satellite.png] Proud Space Junk Award Winner!

Yes you have to apply "Ford sense" to the logistics of the line 50 years ago !!
1) There were multiple lines at DAP. I think it was up to 4 at one point (for 60/70's cars). This is where A/B/C/D comes in for the rotation numbers. Those numbers started a 1 and went to 999 and started over. At FULL production I heard that 900+ cars was possible - but that depends on many MANY factors.

2) Sure we know that supply issues could effect builds BUT Ford was using "on time delivery" of parts long long before it entered the nomenclature of wall street. The Boss 351 and the SVO are great examples of DELAY in "Job 1" (2 weeks for Boss/2 months for SVO late) On the flip side of that would be the special runs of the 135 cars in Dec of 1968 or the promo Pace car coupes built all built on a weekend for Lee Iaccoca.

3) While grouping in Body/paint would often be buy colors (in batches) - to save material and change over constantly.......drivetrain installation was separated so line workers "didn't have 5 Big Blocks" /or AC cars for that matter back to back. (as they took more time with added items or procedures)

SInce the OP is a Boss 351 owner....WE tend to want to know about our cars. Researching these things, as well as RUNNING CHANGES TO PRODUCTION are what restorers have to research to defend WHY a component is used. It takes multiple photos, junkyard pictures, internal Ford documents and original owners (with unmolested cars) to whittle down anomalies. A to that different sub suppliers and finishes and you can see why there are so few restored cars that pass the litmus test!

P.S. Some though done well, then get "all stickered" up incorrectly and makes people question the level of the work done. "If you don't know the difference in a "voltage reading and hydrometer reading" you may be a redneck restorer" Quote Mark Jeff Foxworthy Haas
Ray, I know everyone appreciates your and Rich's efforts in trying to put a handle on the assembly line world. The assembly line of the 60's and 70's is a far cry from what we have now. As archaic as things look to us, especially when compared to present day robotics making laser guided precision measurements and movements, the Big Three some how managed to build hundreds of thousands of vehicles. They were built as good as technology was then.
The Numerical Sequence of Assembly seems to be another one of those "Black Holes". I know for years most people though of the last six of the Vin as the absolute order the car was built. As you well know the cars were serialized not long after the ordered was received. That way the car could be further identified along with the DSO order number as basic build and option materials were put in place for the assembly process. Of course retail sales with preference over stock orders and supplier constraints helped juggle the numbers even more.
I have seen fleet orders such as when the sales dept ordered 50+ police vehicles or large F150 commercial orders where they were run at the same time and were Vin'ed consecutively.  
And as you pointed out, sometimes serial numbered vehicles don't get built. Customers may change their mind on a single or fleet order, Ford may cancel an order for a supplier issue or vehicle content change.
One such large cancellation came after the Tsunami hit Japan March 11, 2011. A plant that supplied the metal flake in the majority of Ford's metallic paints was destroyed. All dealer stock orders were cancelled that involved any metallic colors. Retail customers were offered a no charge alternative color. Since some of the colors were available on all car and truck lines, the existing stock of metallic paints was depleting quickly. So a very large number of already serial numbered cars and trucks were not built.


No Officer...I really don't know how fast I was going, my speedometer stopped at 140!
Great info! Thanks to all.


1971 Boss 351  
1972 Q code 4 speed convertible 
1971 Mustang Sportsroof  351-2V FMX 
1973 Mach 1 (parts car)
The vin is the order number of the car.

I had vin 100004 on a 68 mustang fastback. It was built 3 months after 68 production started.
(05-15-2018, 09:33 AM)barnett468 Wrote: The vin is the order number of the car.

I had vin 100004 on a 68 mustang fastback. It was built 3 months after 68 production started.

Correct.  Excellent example.  It does make you wonder why so long for an early numbered VIN...
Possibly a RETAIL order that required car being held.  Or some parts not available at initial rotation?
Was bucked date close to build date for that car or do you remember?  I think they (68's) were built at two different production plants.

Thanks,  Ray

1971 Boss 351  
1972 Q code 4 speed convertible 
1971 Mustang Sportsroof  351-2V FMX 
1973 Mach 1 (parts car)
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