I have read Lycoming Service Instruction 1304J and wondered if I can expect to find a Form 337 for an engine on the CD the FAA sent me with the aircraft records for a Cessna 172. The engine once had the following on the data tag: O-320-E2CC. I am told the engine was converted to an E2D per the logs.
Source: general aviationAsk Paul: You can’t get there from here