Yes. The last of the series B's used "Vincent" engines and had Vincent on the tank. The change from HRD to Vincent had nothing to do with series B or C, the change was subjected to both series at the same time.Interesting stuff. While I have a Series C with an "HRD" engine are there any Series Bs with Vincent engines?
As far as I can tell, the last "HRD" engine left the factory in November 1949.