Rod knock or Main bearing knock?

[ilikerice]

heat shield coming loose maybe? rattling against the exhaust or undercarriage? when the engine shifts when its under a load could be barely enough for something to touch.. just a thought..

also im wondering if his CAT converter is about to kick the bucket.. just cuz u dont smell rotten eggs doesnt mean it isnt on its way.. but then again, check engine light would come on wouldnt it =(