I have an 02 Dakota 4x4 with a 4.7 and automatic in my shop right now that has a very pronounced knocking noise coming from somewhere (very hard to pin down). The owner says it's been making the noise for a year or so - it honestly sounds like a rod but the engine runs fine, the oil's not burned, no popping back in the intake, just this noise. When I get under it it sounds like it's coming from the flex plate/torque converter/front pump area. I pulled the inspection plate off looking for loose converter bolts but they were fine. I pulled the left exhaust manifold off because it had a broken bolt and found the manifold warped almost 1/8" end to end with the middle high - resurfaced it and put it back together with new bolts, didn't change anything. The noise sounds to me like something rotating (crank, etc) hitting something sheet metal like the pan, but the oil pan is cherry - no dents or bent up areas. No rockers off, chain tensioners appear OK. Truck has 179K miles on it - it just seems like this noise is bad enough that something ought to show up broken but it doesn't seem to be that simple.