10BP

I am assuming the movement was made for a short period in the 1950s as I've seen one other Bulova watch that contained this particular movement and it was a 1957 Bulova Chronograph as seen in the following images:

So I'm assuming the movement was made for most of the 1950s for the high end models only.

I have a Bullova 23-jewel His Excellency dress watch made with the 10BP movement. Very slim case thickness. Manual wind. Sub dial at the 6 o'clock position.

Two L9 NOS 10BP 23 jewel movements with uncut stems and still in the factory shipping movement holders.