The pump with the extra open fitting is for an SRT. I had to tap that unthreaded hole when I changed the pump on my limited. I do remember some one saying the material was soft enough and the bolt hard enough you could just screw it into the hole.
If you do that you are doing it wrong, it will not work like that on this part, buy a cheap tap if it is just going to be used once.
If you are going to do a job, do it right.