If you have the valve cover off you should be able to look down the chain and see chain guides there. If you don't, well then you could be in a little trouble. The chain will eat way at the aluminum cover into the water pump area, then you have more to replace. If you catch it early, then all you have to do is replace the guides. Same amount of work though, just one is spendier than the other. Also, the guide pieces fall into the oil pan, they could block oil flow and is therefor recommended that the oil pan is pulled to get the pieces out. There won't be any slack due to the chain tensioner. You will definitely have to jack the motor/tranny up the get the pan out, but I don't think this is were your problem is. you might want to check the valve clearances. If they loosen up it starts to sound like a small diesel and or clattery. Get a manual for the thing too it breaks it down for you.

A well know guy to get parts from is
www.engnbldr.com He shows up here every once and a while.

Hope this helps