We took off the valve cover last night, nothing appears broken. From the top, it looks like it is all working like it should. I expected it to be full of sludge and was surprised it wasn't. So maybe it is a bearing, which isn't worth fixing. We'll prob do an oil change tonight, an STP or treatment of some sort, and drive it till it dies. Hopefully it lasts a while. Unless anyone has any other ideas. Maybe I'll check the compression, although I'm not sure that will tell me anything at this point. I don't hear the knocking at all when it's just turning over and not firing (all plugs wires removed). Not sure if that means anything or not....could that mean it's not a bearing?