sounds kind of right, but the bottom plate is one of the most important parts of the oil pump.

the pinto one and yb are basically the same, but the yb one has the outlet for the under piston spray bar. however, if your yb pump is old, chances are the bottom plate is worn or scored. putting that one the new pump will make it just as crap as an old pump. i would get the yb plate surface ground back to flat, and then put it on your new pump.