Getting to the finishing stages on my RV-8A, and have question for the knowledgable posters here regarding engine parts. I have a Lycoming O-360A1D that I purchased used for a good price, but it is missing the flywheel/ring gear. I'm trying to buy a replacement, but how do I know what part number to order? Looking at: http://www.lycoming.textron.com/utility/global-resources/Lycoming Engines Parts Price List 2012.pdf I find lots of parts labeled "SUPPORT ASSY-STARTER RING GEAR" for very high prices. Cheaper is: http://www.airtecinc.us/aircraft/index.html which looks like the part on engines I have seen elsewhere. Lots cheaper too. How can I know what part number I need? Do I need to buy the Lycoming overhaul manual or something? Thanks for any help you have.