If you're not sure wether you have an F7 or an F3 unit, look at the four round fans located on the roof of the engine. If the fans are flat and even with the roof then it's an F7, if they're raised and sit higher than the roof then it's an F3. This works for both A and B units.
Guide created: 09/01/06 (updated 02/28/09)

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