In the 90"s every Raleigh factory had a different way of numbering frames, so if the frame number starts with a letter It's a specialist department build, 'A' = 1990 'B' = 1991 etc
Raleigh essentially made bikes for the masses, but some were not meant for mere mortals and were made in the special products division. Dynatechs were one such range, there were others.
