Engine replacement sounds like rocks rolling around in the engine

Had engine replaced on Thursday. Picked up car, and drove it for four minutes. Sounded like rocks rolling around in the engine. What could this be?
I just have a feeling they are going to try to say it is not the engine. I don't see how it could not be. I just had this same thing happen fourteen months ago, and they replaced the engine back then too. I just paid them $2,200.00. I can't afford any more. Any advise/help would be appreciated.