Driving today I ran into an issue. With truck under a little load going over a bridge I heard this clinging of what sounded like metal to metal to me. I can't figure out where it is coming from but it seems like it may be from under the cab? It did this a while back while towing my boat on flat ground. Do you guys think it could be a fin loose in the tourque converter?

 

It might be spark knock. It might be a loose exhaust heat shield.