In my case was a Mercury.
I have never used aftermarket.
Also relevant, in my case I had OEM Gen 7 pumps where they reduced the shaft diameter compared to the older pumps.
The Hardin Marine stainless ones have bigger shafts and use the old impeller.

This is a good point that everyone should take note of too. The merc housings have quite a sharp moulding lip on them that internally that it's worth carefully sanding flush.

Merc's parts are sourced from China now. Needed an idler pulley for 1996 7.4lx MPI raw water pump. Merc's bag printed "made in china" and also stamped on the bearing for their way premium price!

Of course they are, as are most everything, as it has been for years/decades.

There's still plenty of NOS around gotta hunt for it.
EDIT: took less than a minute


https://cimg3.ibsrv.net/gimg/www.off...d209fd288d.jpg