help I need this

OK, I looked at my own link and NAPA indeed shows it out of stock. So maybe that is why everyone else sent you the non-equal reservoir unit.

But here is a question? Why would sending the MC with a bore too rusty to be honed locally will work by sending it to Car-Done? Or is the rust on the outside of the MC. IMHO, they will be quicker to reject a rusty bore than anyone to avoid any liability.
The reservoir need to be the same size for either disk / disk or drum / drum the only difference in the one ur showing in ur address and the one I have is a screw with a tab holding the plunger in mine has a spring clip internally other than that there the same