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Goodbye, Brown Rectangle

by Loring M. Lawrence

from BUS INDUSTRY, Vol. ?, No. ?, 1981, pp. 22-25

The most familiar name plate in American busdom disappears after nearly four decades.

Since 1943, General Motors busses have been identified by a brown and silver serial number plate mounted on the interior bulkhead near the front door. Measuring 11 1/2 by 3 13/16 inches, this five-ounce aluminum plate became, to bus enthusiasts, the most familiar and favorite trademark of North America's leading bus and coach manufacturer.

Last year, a combination of three events caused the brown rectangle to disappear from GM bus production in both the United States and Canada, ending a thirty-seven year tradition. In the U.S., the last one was applied in late June; in Canada the final brown rectangle was riveted during the spring of '80.

When GM brought out its futuristic RTS city bus in 1977, a stylish RTS serial plate was created to harmonize with the vehicle's revolutionary design. The close out of "new look" production at Pontiac thus ended the era of the brown rectangle on GM's transit and suburban busses. Meanwhile, GM's intercity coaches, models P8M-4905A AND P8M-4108A, were redesignated H8H-649 and H7H-641 (none of the latter were built) to correspond with the revised RTS model nomenclature. But declining orders forced GM to announce, in June 1979, that its intercity line would be discontinued. Their last parlor coach, an H8H-649 for Eastshore Lines (San Francisco), left Pontiac in early July 1980 and was thus the last U.S.-made GM with the rectangular brown serial plate.

In Canada, Diesel Division, General Motors of Canada Ltd. used a serial number plate very similar to the U.S. design. Bus production had commenced at GM's London, Ontario plant (which also built trucks and diesel locomotives) in 1961; it was transferred to a new plant in the Montreal suburb of St-Eustache in 1979. Only transit [and suburban]-type vehicles were built in Canada; Canadian orders for coaches were always filled at Pontiac.

Effective 1 September 1980, new Motor Vehicle Safety Standard regulation (MVSS-115) specified a standardized vehicle identification number (VIN) of seventeen alpha-numeric characters. For GM of Canada, it meant the end not only for GM's traditional serial number, but of the brown rectangle as well, for the plate contained insufficient space for a seventeen character code. Coach model designations would remain unchanged, however.

GM of Canada used the opportunity to design a new serial number plate compatible with Canada's French and English bilingualism. By using the Diesel Division and GM logos and the bilingual abbreviation "mod" for model, a clear attractive and understandable serial plate resulted.

Forseeing the changeover, the brown rectangular plates were phased out during the spring of 1980. For a few months of production, busses were thus fitted with the new polished aluminum plate yet bore the traditional style serial number. The first bus with the new plate and full VIN code was the lead bus in order M-190 which was a T6H-4523N for Lane Transit District in Oregon. Its formidable VIN was 2GHYT72W8B3500001.

Old and new Diesel Division, General Motors of Canada serial number plates are compared. Company headquarters remained at London (Ontario) and continued to to be imprinted after the bus facilities moved to St-Eustache (Quebec).

(Photo by Peter Newgard)


General Motors of Canada applies a sequence number in four locations on each bus, and each was modified to conform to the seventeen-character Vehicle Identification Number.

The vehicle identification number plate is located on the engine bulkhead on the right hand side of the transmission. To comply with MVSS-115, only the seventeen digits are required. Space is also provided to indicate gross vehicle weight (in pounds) and maximum front end and maximum rear end weights at ground. This information, plus delivery date, is required only on busses delivered in the state of California.

Second is the certification label which appears on the side wall above the driver's position. Information on this label was revised to include the VIN code. The model designation was retained, but the serial number, as such, was deleted.

Third is the serial number plate, located by the step-well. This is now imprinted with the model designation and the last six digits of the VIN code, which are now the sequence number.

The fourth location is on part of the frame itself--actually the right-hand bellows beam. Production people have engraved model and serial numbers on this beam with an electrical pencil. As in the other instances, this serial number is now replaced by the seventeen-digit VIN code.

The government imposes a fine of $10,000 for each incorrect VIN code.

Deciphering the new VIN code requires a detailed explanation. The seventeen digits cover ten items of information. We will discuss each in turn, using VIN 2GHYT72W8B3500001 as a example. The following information is that applicable to, and furnished BUS INDUSTRY by, General Motors of Canada.

  1. Positions 1, 2 and 3 indicate the maker identification code. 2GH indicates a bus built by GM of Canada; 1G0 would indicate a U.S. GM bus, and 1GG a U.S. GMC bus chassis. Thus

2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1

  • Position 4 indicates the brake system: Z for hydraulic and Y for air.

    2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1

    A close-up of the new bilingual serial number plate of Diesel Division, General Motors of Canada. This specimen, of T6H-5307N for the Laval Transit Commission (number 370) was completed before the seventeen-digit VIN was required, and is serial M1799.

    (Loring Lawrence photo)

  • Position 5 indicates chassis type: T for transit type and S for suburban.

    2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1

    The vehicle identification number plate, on a GM Truck & Coach RTS built for Merrimack Valley Regional Transit Authority. The serial, on bottom, is 1G0YT76W0BV810505.

    (Photo by Loring M. Lawrence)

  • Position 6 indicates length of vehicle: 6 for 30-foot body length, 7 for 35-foot and 8 for 40-foot.

    2 G H Y T 7 6 W 8 B 3 5 0 0 0 0 1

  • Position 7 indicates width of vehicle: 6 for 96 inches, and 2 for 102 inches.

    2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1

  • Position 8 is the engine code: H for 8V71 diesel, J for 6V92 diesel, and W for 6V71 diesel.

    2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1

  • Position 9 is a check digit. It is calculated after all other digits are assigned.
    1. Assign to each number in the VIN its mathematical value and assign to each letter the value specified in the table below.
      A = 1
      B = 2
      C = 3
      D = 4
      E = 5
          F = 6
      G = 7
      H = 8
      J = 1
      K = 2
          L = 3
      M = 4
      N = 5
      P = 7
      R = 9
          S = 2
      T = 3
      U = 4
      V = 5
      W = 6
      X = 7
      Y = 8
      Z = 9

    2. Multiply the assigned value for each character in the VIN (step A) by the weight factor specified in the following table.
      1st - 8
      2nd - 7
      3rd - 6
      4th - 5
          5th - 4
      6th - 3
      7th - 2
      8th - 10
      digit - 0
      10th - 9
      11th - 8
          12th - 7
      13th - 6
      14th - 5
      15th - 4
          16th - 3
      17th - 2

    3. Add the remaining products and divide the total by 11.

    4. The remainder is the check digit. If the remainder is 10, the check digit is X.


      VIN character:1G1AZ3728BJ123456
      assign value:17119372821123456
      weight factor:876543210098765432

      The total of the sums shown in the bottom line above is 250.

      Divide by 11: 250/11 = 22 + 8/11

      The check digit = 8 (position 9)

      2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1

  • Position 10 is the model year. Note that this now corresponds to the automotive year, not the actual calendar year of construction.

    From 1 September 1980 to 31 August 1981, assign year 1981 = code B. From 1 September 1981 to 31 August 1982, assign year 1981 = code C. Year codes are an alpha or numeric character which repeat in thirty year cycles.


    2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1

  • Position 11 indicates assembly plant: 3 is St-Eustache, V is Pontiac.

    2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1

  • Positions 12 to 17 indicate sequence number. Each year the sequence number starts at 500,001 and continues in sequence with each successive bus. The next year it starts again at 500,001. These digits may be referred to as the serial number. The seventeen digits together are the vehicle identification number.
    2 G H Y T 7 2 W 8 B 3 5 0 0 0 0 1