Andrew Turnbull presents

The History of School Transportation in Mercer County, WV


Technical Information: Deciphering VINs

Thomas

school bus

1981-1991

Thomas' Type D buses of the 1980s aren't exactly common survivors. Making matters worse, Thomas' VIN system of the 1980s is almost inscrutable, since no reference source is readily available. This analysis was scraped together mostly from observations alone:

1T7C3D481C1752772

Positions 1-3 and 11: Manufacturer and assembly plant

1T7-1 Thomas, High Point, North Carolina (US)

Whether Thomas ever built complete buses at its Woodstock, Ontario satellite plant is anyone's guess.

Position 4: Body length

Similar to Blue Bird, Thomas used model designations in this era where the first two digits were the same as the body length in feet:

Model Sections Max capacity
A 3399 11? 66?
B 3649 13 78
C 3885 14 84
D (seen on non-school buses)
E 3935 14 90
L 3659 13 78
M 3895 14 90

Position 5: Type

2 Non-school, high headroom
3 School, low headroom
4 School, high headroom
6 Non-school, unknown details

Position 6: Engine

This list is incomplete, and probably has a few errors...so take it with a dash of salt:

2 5.9L I6 Diesel (Cummins)
3 10.4L V8 Diesel (Caterpillar)
B 9.1L V8 Diesel (Cummins VT-225)
D 10.4L V8 Diesel (Caterpillar)
G V8 Diesel
H 10.4L V8 Diesel (Caterpillar)
J 10.4L V8 Diesel (Caterpillar)
K Unknown
M 8.3L I6 Diesel (Cummins)
R 5.9L I6 Diesel
V I6 Diesel (Cummins)

Positions 7-8 and 12-14: Production sequence

The sequential number in the VIN is the five-digit order number of the bus, assigned prior to manufacture. It also appears as the leading portion of the lengthy body identification number (i.e., "65980-28901-RE-3885S") engraved on the certification plate of Thomas products.

During the 1980s, Thomas order numbers progressed from the 40000s through the 90000s. Order numbers were assigned to all buses, including conventional models built on outside chassis. Thus, most were never used in VINs, and any list of Thomas VINs will have numerous sequential gaps.

Position 9: Checksum

0-9 or X, calculated from the other digits.

Position 10: Model year

Thomas appears to have aimed for industry-typical September model year transitions in this timeframe.

B 1981
C 1982
D 1983
E 1984
F 1985
G 1986
H 1987
J 1988
K 1989
L 1990
M 1991

Positions 15-17: Unknown

The trailing digits of the order number are followed by three seemingly-random numeric digits of unknown significance.


1991-present

Finally, a bit of order to lend method to the mayhem! Thomas Built Buses changed to a more straightforward and better-documented VIN format late in the 1991 model year.

1T79R4B26N1112325

Positions 1-3 and 11: Manufacturer and assembly plant

For reasons that elude me, Thomas' manufacturer prefix is contingent upon the configuration of the product:

1T7-1 Thomas, High Point, North Carolina (US) Rear engine
1T8-1 Front engine

Position 4: Model

5 ER (1992-2001), HDX (2001-03)
8 EF (1995-2012), EFX (2013-)
9 ER (1992-95)
H ER (1997-2003)
Y ER (2001), HDX (2004-)

Position 5: Body length

In 1991, Thomas' body model numbers changed from expressing the length in feet to expressing the length in body sections. As before, these body sections correlated with capacity. Note that the equipped capacity of a bus is almost always lower than the maximum capacity of the body, due to the need for open space around entrance and emergency doors.

Sections Max capacity
G 9 54
J 10 60
L 11 66
M 72
N 12
R 13 78
S 84
T 14
U 90
W 12 78
8 14 84

Position 6: Type

2 Non-school, high headroom
3 School, low headroom
4 School, high headroom
9 School, EFX

Position 7: Engine

A Diesel (Mercedes-Benz)
B I6 Diesel
C Diesel (Caterpillar)
D 6.7L I6 Diesel (Cummins)
E 8.9L I6 Diesel (Cummins)

Position 8: Brake system

1 Hydraulic
2 Air

Position 9: Checksum

0-9 or X, calculated from the other digits.

Position 10: Model year

Thomas Built Buses retained a September model year cutoff through the first half of the 1990s. From that point on, the calendar started creeping further and further forward. MY1998 began by May of the year before; MY2000 began by February. By MY2005, the cutoff had migrated two calendar years in advance. And that's where things stand today, although Thomas' model year schedule remains a wee less exaggerated than corporate parent Freightliner's.

M 1991 2021
N 19922022
P 19932023
R 19942024
S 1995
T 1996
V 1997
W 1998
X 1999
Y 2000
1 2001
2 2002
3 2003
4 2004
5 2005
6 2006
7 2007
8 2008
9 2009
A 2010
B 2011
C 2012
D 2013
E 2014
F 2015
G 2016
H 2017
J 2018
K 2019
L 2020

Positions 12-17: Production sequence

As before, the sequential number in the VIN correlates with the order number of the bus. Order numbers proceeded continuously from year to year (with a bit of overlap) and initially adhered to a five-digit length, resetting from 99999 to 00000 three times before being expanded to six digits in MY2017.

The VIN, however, has always contained a six-digit numeric serial...and Thomas has often played games with the leading digit, periodically skipping or backtracking as follows:

This information applies to Thomas' Type D buses, and specifically those built on in-house chassis. Thomas' newer Type C buses are built on Freightliner chassis, and continue to use the Freightliner VIN format.



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