I'm looking to purchase a 1967 Thunderbird for the drive train, But only if its a 428 engine. The 5th digit should be a Z or a Q but the guy swears its a O. Its almost impossible to tell a 390 from a 428 unless you disassemble the engine. I was told if its a 428 it would have a ( A ) welded on the back of the block. Did they make a 4 door Thunderbird with out AC with a 428 ?? Also it only has a 2 barrel carb. The guy swears the old man bought the car new and may have ordered the car with a 2 barrel ?? Anything special I should look for ??