Aircraft Modeling

Hello, I'm an occasional Flight Simmer for the last few years, but am getting more into the "cockpit" witht the release of FS9. My question is this: Where do I go to get an actual flight model for FS9 aircraft? For instance, if I want to fly a 727-200, where do I go for the flight model file? How do I know the file I'm downloading contains the modeling, and is not just a 737-300 flight dynamics in a 727's "clothing"?Thanks for your assistance, and look forward to dealing with you folks many times in the future.Eddie