During 1969 a new number system was introduced which used a two-letter prefix indicating month and year, followed by the model type and the serial number. The first letter is the month, the second the year. This system used the triumph model and year not calendar year, which ran from August of the previous year to July of the current year. From July 1980 a third letter A was added to allow the system to keep going. Many model types included a V which designates a 5 speed gearbox.

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For Example: T140V HK12345 - is a 5 speed T140 Model built in July of model year 1974/75.

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Also T140E NDA12345 - Is a T140E model built in October of model year 1982.