I've posted some new Data Tag Project info on three Class C Barths which were previously unrecorded. A slightly interesting fact emerged.

I had always thought that Barth ceased production of the 19M in 1975, and commenced the 22M in 1976. But one of the new data tags is for a 22M with a date code of 7506 and a serial of 1690. The database currently includes a 19M with a date code of 7506 and a serial of 1689, so these two units might be the last 19m and the first 22M made, both released in June 1975.