#### Rudie

**Staff**

Up to 69, usually simply look at the beginning of each parts book (e.g. British Only Tech Library), an early page in each gives the starting engine number of the model year. Subtract the number in one parts book from the the number in the following year's parts book and you usually have the number built in the model year.source I can look at for each model build for those numbers? 68-69, thanks if you can help.

That only works up to 69 because each model range used a separate number sequence, although it doesn't break down the numbers into separate versions - e.g. T120, T120R, TR6, TR6R, TR6C in the 650 range. It also assumes Meriden did not build a large batch of bikes for one customer before starting on the 'civilian' bikes; e.g. simple subtraction does not work for 66-67 C-range because Meriden built over 1100 3TA's for the Dutch Army before starting on the 67 range, the engine number in the 67 parts book is the first 'civilian' engine.

68 onwards, BSA used the same number sequence for both BSA and Triumph 250's. October 1968 onwards, Meriden used the same number sequence for all twins built there, irrespective of whether they were 350, 500, 650 or 750. You can still get an idea of some annual numbers from the parts books but it is less reliable than before 69.