Identification hub

GM muscle identification: VIN, cowl tag, engine stamps, and date codes

This hub covers Chevrolet Chevelle, Camaro, Nova, Pontiac GTO, and related GM cars of the mid-1960s to early 1970s. Facts below are limited to what the cited sources support. Year, plant, and model exceptions are common.

A VIN or cowl-tag decode is a reading of factory codes. It is not proof that a car is genuine, and it is not by itself a numbers-matching check. The Camaro VIN, for example, does not identify Z28, SS, or RS.

Official VIN — location

On a 1967 Camaro (and typically on earlier GM cars in this period), the VIN plate is on the driver-side A-pillar and is visible with the door open. Starting in 1968, and through 1972 on Chevelles, the plate was moved to the top of the dash on the driver side, visible through the windshield. On Chevelles, the plate is riveted to a special bracket with distinctive “rosette” rivets.

Sources: Camaro Research Group, VIN / cowl tag decoding; ChevelleStuff, 1968 VIN.

Official VIN — format (13 characters in this era)

A typical 1968 Chevelle VIN such as 138378A160163 breaks down as: division (1 = Chevrolet); series (38 = SS396 in this example); body style (37 = 2-door sport coupe); year (8 = 1968); plant (A = Atlanta); and a six-digit sequence that started at 100001 at U.S. Chevelle plants. On the VIN, an odd third digit indicates a 6-cylinder and an even third digit a V8. The sequence is an assembly-plant sequence across series, and the same last six digits can appear at more than one plant.

A typical 1967–69 Camaro VIN such as 124379N506070 breaks down as: 1 = Chevrolet; 2 = Camaro; 3 = 6-cylinder or 4 = V8; 37 = coupe or 67 = convertible; year digit; plant (N = Norwood, L = Los Angeles); and a six-digit sequence. Camaro start numbers were 100001 for 1967, 300001 for 1968, and 500001 for 1969. The Camaro VIN does not identify Z28, SS, or RS.

Sources: ChevelleStuff, 1968 VIN; Camaro Research Group.

Pontiac, Oldsmobile, and Buick used the same general 13-character GM VIN idea with different division digits. Always decode against a year- and division-specific table; do not reuse Chevrolet series codes on a GTO or 4-4-2. Pontiac factory invoices and option documentation for 1961–1986 are commonly ordered from Pontiac Historical Services.

Cowl / trim tag (Fisher Body Number plate)

The cowl or trim tag is a small aluminum plate riveted to the driver-side firewall in the engine compartment (on first-generation Camaros, by the master cylinder; ChevelleStuff documents the Chevelle tag on the firewall). It was stamped by Fisher Body, not by the vehicle-assembly division. Typical fields include a body build-week date (month digits plus week letter A–E), a style code, a plant abbreviation, a Fisher body unit number, interior trim, and paint.

Do not treat the Fisher style code as a copy of the VIN. On Chevelles, the series on the trim tag does not have the same meaning as the VIN series, and the third digit on the tag does not identify 6-cylinder vs. V8 the way the VIN does. On 1968–69 Camaros, the cowl-tag style was 12437 or 12467 for both L6 and V8 cars; the third digit is not the engine code.

1967 was the only first-generation Camaro year whose cowl tag included a list of Fisher body option codes. Mid-1969 Norwood Camaros added “X” codes (and some Z10/Z11/D80 markings) that help with body trim and some SS/Z28 paint-and-trim differences, but they still require care — X11 is not automatically an SS.

Sources: Camaro Research Group; ChevelleStuff, 1968 trim tag.

Engine stamps, casting numbers, and date codes

On Chevrolet V8s, the engine assembly / suffix-code pad is a machined pad that is a forward extension of the passenger-side block, at the bottom of the forward end of the head. The stamp typically includes plant, assembly date, and application suffix. Inline sixes are stamped on the passenger side near the forward end, close to the distributor.

The block casting number is commonly on a rear ledge of the block (often the driver side). The casting date is normally on the rear of the block where the bellhousing bolts up, behind the distributor boss; some big blocks have the date near the engine mounts or freeze plugs on the passenger side. The casting date must be before the engine assembly date.

A partial or derivative VIN on the engine was not universal before 1968. ChevelleStuff notes that before January 1, 1968 there was no general federal requirement, and Chevrolet plants generally stamped high-performance small blocks (such as L79) and, typically, big-block V8s. Beginning with 1968, more engines were stamped, but plant practice still varied — some 1969 Atlanta and Kansas City engines were stamped on the rough-cast area by the oil filter rather than only on the pad. A matching suffix proves the engine is the correct application, not that it is the original engine.

Sources: Camaro Research Group, drivetrain decoding; Mortec, Chevy V8 casting locations; ChevelleStuff, partial VIN locations; HOT ROD on “numbers matching”.

Transmission, hidden body stamps, and GM date-code letters

Partial VINs also appear on many transmissions and, from 1968 on, often on the Chevelle firewall under the heater or blower area. Frame “CON VIN” stamps exist but can be hard to read with the body on the car. Locations vary by year and plant; Oshawa Chevelles, for example, have not been documented with a heater-box firewall stamp. On 1967–69 Camaros, hidden partial VINs are typically on the cowl under the cowl vent panel (passenger side) and on the firewall below the heater or A/C box. Not every 1967 engine and transmission was stamped.

GM date-code convention: month letters on cast dates run A–L and include I (I = September, L = December). Month letters on stamped component dates skip I (J = September, M = December). A typical stamped date is year-month-day (for example, 8C26 = March 26, 1968). A typical cast date is month-day-year (for example, B129 = February 12, 1969).

Sources: ChevelleStuff, partial VIN locations; Camaro Research Group, including GM date code formats.

Paperwork

When original and VIN-matched, a Chevrolet Protect-O-Plate, build sheet, window sticker, or dealer invoice is stronger than a tag decode alone. The Protect-O-Plate repeats VIN and drivetrain codes; replacement warranty plates may lack drivetrain data. For Pontiacs, order the factory documentation packet from Pontiac Historical Services using the VIN on the car. The cowl tag still matters for body, paint, trim, and build week, but PHS is the usual path to original equipment confirmation.

Sources: Camaro Research Group; Pontiac Historical Services.

Use the multi-make numbers-matching checklist for a field sequence that also covers Ford and Mopar.