Here’s the back story, bought a 145k mile truck for parts, kept motor for my 4x4 Ram 50. Had a blown head gasket, had fresh head done, wanted to replace oil pump and all seals etc. I was very concerned about aftermarket oil pumps since I couldn’t get a melling or Mitsubishi and here I am lol... I bought a enginetech off rock auto. Pump didn’t feel smooth before I put it on, thought it was because it was dry. Well got it all bolted up and even put some oil in it and it’s hard to turn or notchy almost like a bent Silent shaft? I was trying to set the timing in oil pump gear with timing belt when I realized it. It not smooth at all and won’t fall to either side so I can time it correctly. Needed up removing everything and sticking the old pump back on the engine and it’s 85% better I guess I got a bad pump? My luck.