I am sorry to tell you that 47-86462A-1 is no longer available from Mercruiser.
Mercruiser recommends that you replace the whole pump with a 466-9410A-1. This is available from Mercruiser, but it is expensive (see attached quote).
I did find a person who has one of the earlier impellers 14-86462 in stock. They want $150 for it.
Let me know what you would like to do.