any Yanmar dealer
any Yanmar dealer either has this part or can get it for you. I would change it out even if the other one is good. Then you can clean up the old one and save it for a spare.Be sure to order an exhaust gasket when you get the elbow. There is also a coupling that you may want to consider getting. The coupling has a right hand and a left hand thread. Getting the elbow seperated from the exhaust manifold can be a real bugger. It is best if you have access to a large vise, a large pipe wrench with a breaker bar and a torch. When you put them back together be sure to coat the threads with never-sieze compound.