I was reading through some of the archives on articles concerning the 390 and I came across a thread saying that the C6 was never offered with a cast iron housing. Is this true? I bought my 67 motor with the so called C6 on it and I was told this it was a better C6 because the housing was cast iron, not aluminum. I dont know how to tell the difference between the cruise-o-matic and the C6.