Take a look in the yellow pages for a saw shop or small power tool dealer. Consumer saw bars come in various lengths and use just a couple different types of chain. Take in the saw for an evaluation. They will have what you are looking for, and may even be able to upgrade you from a laminated to solid bar. Also, while you are at it, get rid of the original safety chain and put a saw chain on that can cut wood. You will be amazed at the difference. The tree might even fall away from the bar so it doesn't bend.