Hi Christopher,
the horn button shown was used in 1949 - 1951 Frazers, all models.
The one used in 1947/48 Frazer standards was different. The one used in the 1947/48 Manhattans looked similar but it was not the same. Here's a picture of the one that was used in the 1947/48 Frazer Manhattans:
I recall someone reproduced the 1949-51 Frazer type in the 70s, I don't recall who or how you can tell the repros, but if I remember correctly the repros were very good.
