Krewat, no flames intended, but just who is this long island 'guru' ? I think he either doesn't know what he is talking about, or he is blowing smoke up your backside. Anyone who has built 'hundreds' of FEs will know that the 390 and the 360 have interchangeable balancers and flywheels. Maybe your brother used some nonstandard parts when he rebuilt the 360 ? Maybe he thought he had a 360 and was mistaken? something ain't right here......DF