Ka24de intermittent soft knock

[Crookedribs]

My truck has learned a few tricks lately! Including rollover and knock knock jokes. It sounds like its coming from the rear of the engine. No shavings in the oil, it pretty much disappears when you load it down, but it can be heard as long as the rest of the engine is quiet. It doesnt have any rhythm either. It just knocks for a couple seconds, and then knocks for a couple more seconds and so on. I thought it could be my mains, but it also seems like it could be some sheild rattling. The b**** runs hot too. Always has, even after replacing the waterpump, rad, hoses, thermo, and cleaning the block out.. ?.?