Hi Isle of Wight, our 2001 #851 engine is close to reaching 1000 hours. What service have other C320's with 3GM30 engines done and if done by others, about how much did it cost and how long did it take at the 1000 hour point. Our engine runs fine, Our manuals are on the boat in MD on the hard and we can't get to them easily. Irv Grunes