I'm getting a used 039 that has a 25 inch bar and chain and I would like to drop down to an 18 inch. I've never bought a bar before. I know there are different gauges and chain pitches. So which is best? Also what are some things I should check on the saw? I know the obvious like filter and spark plug. What about the clutch? What do I look for? I've messed with saws since I was 10. Bought my first one at 12. I use to help my dad and grandfather cut wood. That's all the heat they had. I was never taught anything about gauges and chain pitch. Actually they didn't show me much lets say technical stuff. I guess I was raised where you didn't back talk or ask many questions. Seen but not heard I guess. I wish they would have taught me more. So I'm trying to learn as much as I can now. Thanks for any help you can provide and I love the forum.