I'm guessing my AE-1P has it. It certainly has something. It's in the mirror mechanism; local shop said it's the bearing(s), and they quoted $120 to repair it. That's more than I paid for the camera and both the lenses I have for it combined, so I'm going to ignore it 'til it seizes, then decide what to do with it.
For the record, it sounds kind of like "ker-WREKHewww", or sometimes "wrekkheych!", except higher-pitched.