You may want to look into haveing a used engine installed. Are you willing to do some work on the truck yourself, or prefer to take it to a garage? I am just about to replace the primary timing chain tensoner on mine, and this shoud be quite the adventure. I am expecting the balance shaft chain tensioner to be shot as well. That means lifting the engine and droping the front axel to get the oil pan off. That is why I have put it off. Mine does not rattle at idel, so I expect your issue is at a more advanced stage