Trim Tag Facts
SS and SS396
From 1964 through 1968, the Super Sport (SS) was a separate series. The 1964 Malibu SS could be ordered with a V8 (VIN starts with '458') or L6 (VIN starts with '457'). The 1965 Malibu SS could be ordered with a V8 (VIN starts with '138') or L6 (VIN starts with '137'). The 1966 through 1968 SS396 series was only available with the 396 engine (VIN starts with '138' and includes body styles '17' and '67' for 1966 & 1967, body styles '37', '67' and '80' in 1968 only).
The 396 engine could be ordered in the 1966 and 1967 El Camino as regular production options L35, L34, or L78, but they did not have the SS option package; the SS El Camino did not appear until 1968 and 1968 was the ONLY year you can verify by the body plate and/or VIN as being an SS396 El Camino as the series/model is 13880.
It should also be noted that just because a VIN may start with '138' does NOT indicate it's an SS396 Chevelle. Beginning in 1967, the Concours station wagon VIN also began with '138' but the body style designation was either '35' or '45' depending on the seating arrangement; the Monte Carlo also used a VIN beginning with '138' but was available only in one body style number, '57.'
Style Correlation to VIN
The Fisher Body style designation from many plants/years on the body plate DOES NOT indicate a 6-cyl. or 8-cyl. engine for a series such as '35' or '36' for a Malibu. For example, a 136xx style number on the Fisher Body plate does not mean a V8 engine was installed in the vehicle. You must check the VIN to see if a 6-cyl. or 8-cyl. engine was originally installed. There are numerous examples throughout this site of even numbered series on the body plate (e.g., 13469) and the VIN shows an odd number (e.g., 13369) indicating a 6-cylinder engine. There are also numerous examples of odd numbered series on the body plate (e.g., 13569 in 1971) indicating that not ALL Fisher Body plates used even numbered series indications. See this page for more detailed information on Fisher Body Number plates.
The exceptions to the above is any 1966 through 1968 body plate with style/model numbers of 13817, 13837, 13867, and 13880 in 1968 only. The SS396 was a separate series in the Chevelle lineup during these years and ONLY available with the 396 8-cyl. engine. Trim for a '38' series SS396 was different from a '36' series Malibu, hence the body plate on a 1966 to 1968 SS396 Chevelle (or 1968 SS396 El Camino) will show the '38' series and definitely be an 8-cyl. Chevelle. The 138xx Concours Station Wagon series is, naturally, not included in the SS396.
In 1966 and 1967 only, the SS396 also had its own body style designation (model) for the 2-door sport coupe and can be identified on the body plate and VIN with model number "17" in the model designation as opposed to 64/65 and 68/72 which used model "37" to denote the 2-door sport coupe. The "17" indicated the new strut back styling of the top.
Not all assembly plants used the same format on their Fisher Body number plates. Some early Chevelles/El Caminos (64-67) had option groups, some plants did not include those. Some used 'A' or 'B' to denote bench/bucket seats even though the trim code used was only for bench/bucket seat type, some plants did not use 'A' or 'B'. Please check your plate for the assembly plant and compare to sample plates I have throughout this site.
Body Assembly Date
Body assembly dates should be considered with caution. The format of NNL (number-number-letter) is the month number "01...12" (sometimes only a single month number is used) and a letter "A...E" designating the week. A lot of speculation has been made about exactly what constitutes a 'week', or rather, what week is "A" or "B", etc.? It appears as though, for the most part, most assembly plants worked 2 shifts Monday through Friday during this time period.
There is no known formula for saying what week letter goes with what week in any given month in any given year; I've tried them all. One theory is that the "A" week is the first full week of a month that starts on a Monday. Another is if the start of the 'following' month is Tuesday through Friday (say April 1 is on a Tuesday) and the previous month (March 31) ends on a Monday through Thursday, the month and week are depicted as April and the first week (04A) while another theory is that same car would have the last week of March (03D or 03E). The trouble is if you accept either of these explanations, it becomes invalid in a month or two.
Trim tags are made up before production is
started but the car is scheduled to be built. The trim tag is installed
on the Fisher Body side of the plant early in its assembly. If for some
reason it's pulled from the Fisher Body side for repairs such as poor
fit, paint, etc. the trim tag doesn't get changed even though the car
itself may be delayed. I have several examples of trim tags with a later
body assembly date but the car has an earlier VIN. Example, two 1967
Atlanta Chevelles with trim tag dates of 09D falling between two trim
tag dates of 09E and the sequence number puts them there.
09E ~ 107931
09D ~ 108206
09D ~ 109494
09E ~ 109928
The trim tag date is when the body shell was welded together at Fisher Body, not when the body finally got to Chevrolet and went through final assembly. Typically it took 2 days (4 shifts) to go through the Fisher Body process and another 1-1/2 day (3 shifts) for the final assembly process.
High-work content options/styles weren't "batched", as it unbalanced the main assembly line (like running two or three convertibles in a row on the Fisher side or many A/C's or bucket seat/console jobs in a row on the Chevrolet side); that's why there was a schedule bank between the Fisher side of the plant and the Chevrolet side, so the high-work content stuff could be scheduled to the main line at predictable intervals so individual line operations didn't get over-cycled.
You also need to consider whether the car was built at a traditional Fisher Body/Chevrolet plant (where each plant was separate, and they were operated by two different GM Divisions), or whether the car was built at a GMAD (GM Assembly Division) plant. GMAD plants were operated by one Division, and their operations/processes were integrated based on what made sense for the assembly process, not by whether the parts and tooling were released by Fisher Body or by Chevrolet. GMAD plants had total control of the assembly process and production scheduling from the first welding fixture in the Body Shop to the roll-test machines, and had much more flexibility in how production was scheduled and tracked; they operated differently (and more efficiently) than the Fisher Body/Chevrolet plants.
There is no absolute relationship between the cowl tag and the calendar. The build date was for Fisher's use and they changed the date at their discretion.
A week is a generally a week in the body code, you just can't say that the "A" week started on the 1st of the month, or the "E" (or "D") week ended on the 30th of the month.
Generally the "A" week of the month is the first FULL calendar week of a month. For example if the month ended on a Tuesday, then that whole "assembly" week was part of the previous month even though there was only one calendar day in that month. There are exceptions to that statement and differences from one assembly plant to another so itís not really worth worrying about. Using the VIN numbers (at least for 69 and later cars) is a much better way of determining when in a month a particular car was built.
It's also been noted that the body assembly unit numbers appear to be sequential to the body type (2-dr Malibu sport coupe, convertible, etc.) through model year 1969. From 1970 through 1972, the body assembly unit numbers are not sequential.
Beginning in 1972, the Chevelle VIN plate changed
to (1) a single letter indicating the basic model (Malibu, Chevelle,
El Camino) and (2) a letter after the body style indicated the engine
installed in the car. The Fisher Body plate DID NOT change from
previous years. Where a 1972 VIN might read "1D37U" for a
Malibu 2-dr sport coupe with a 402 engine, the same Fisher Body plate
would still read "13637" with no engine size specified.