Machine numbers are composed of a model number, a two character date code and a five digit serial number. On some models, the model number is a prefix and on others it is a suffix. For example:
T160NN43128
CH27346T150V
The actual month of build is shown by the first letter. The second letter gives the model year.
Production for sales in the following year began in August, so the prefix NH indicates a 1973 model built in October 1972.
Frame and engine numbers matched when the machines left the factory.
| First Letter | Second Letter |
| A January | C 1969 |
| B February | D 1970 |
| C March | E 1971 |
| D April | G 1972 |
| E May | H 1973 |
| G June | J 1974 |
| H July | K 1975 |
| J August | N 1976 |
| K September | |
| N October | |
| P November |