[Zero10]

I suppose from what you say, it sounds like a #2 bearing. It's strange it would fail when just driving on the highway. Usually they fail in hard cornering at high revs. That is, unless the car has seen a lot of hard driving, and the bearing was already badly worn from that.

If you have very little oil pressure, and it's knocking like a diesel, then definately pull it apart to see what's up.
Check out the oil (like you said), and if it's still good, then perhaps it is something else, but if the bearing spun, you should have some metal shards.