Catalytic converter making a rattling noise when accelerating is indicitive of?

[Knightwulf]

As the title states... Unfortunately, I don't know much more about the issue as this was all the information I was provided about the vehicle in question.

I'd like to have some idea of what might be causing this; what questions I should ask in order to have a more definitive idea of what the problem might be and/or what the possible repair costs for something along these lines might entail.

This is a vehicle I'm considering purchasing as seems to be about the only blemish on it.

It has 114,000 miles, the transmission was rebuilt at 80,000. The interior is in prime condition and the seller has a complete history of all maintenence.

As always.. All help/assistance/advice is appreciated.

--Wulf