440” small block, pump gas, street car...

Your nipples are cast into the aluminum. Mine were threaded into the cast iron pump. The easiest thing would be throw a couple of rubber caps into the glove box. You could take the caps off and put some epoxy into the nipples, you just don’t want it moving down into the impeller. You might be able to thread the inside of the nipple for a screw in plug. You don’t want to break the pump. I just have had one pop.