Deep engine knock is bothering me

My truck has a knocking and rattling sound. It sounds like it is coming from the oil pan next to the oil pump.I changed the pump but still the same problem. It doesnt sound like its a valve knock but again sounds like its coming from the oil pan by the pump. It just keeps knocking as soon as I start the truck.I did drop the oil pan and change the pump but same problem. However I did notice that while changing the pump there was a piece that seemed loose. I dont know what this is called but I will try to explain it. To the right of the pump there is a metal bar like that goes up and hooks to some kind of bar now this piece has another one that looks just like it next to it but turned a different way and it has these the length almost of the oil pan. From what I can tell only the one piece like this is loose next to the oil pump.I dont know if thats causing the knocking or not and if so in your opinion will be expensive to repair?