Could someone help with my edification and tell me what pump this mechanism would have been on?

Thanks
Ron

Wayne visible pump mechanism.

I bought a base from the seller that has that mechanism. It looked to me like somebody modified the shaft by making it round.

I have one just like it , and did one recently from a wayne 519 , but have one here from a clear vision I also restored , and have seen it in other pumps also

Here is a 615 I'm working on and it looks different than yours.

les is correct , The one for the wayne 519 looks like his , a metal U clamp went around the top flat place to hold the pump in ,