"X" stamped 440 block???

[68ChargerJMP]

You know how these stories go about someone who says they have this or that whe comes to rare stuff. Well, today I went to throw some disc golf and when I pulled up, much to my surprise, there sat a 70 SuperBee,383 pistol grip 4-speed. Me and the owner shot the breeze for a little while, and he mentioned another car he had that had a 440 that was stamped with an "X-1". He said hes never read anything about it in any Mopar magazine or seen another one. I dont know that Ive heard ot it either, but I am curious about it. Does anyone have any idea what the "X-1" stamping means?

[BigBlockSam]

that means it's special ,   

[Troy]

Year One says it means "oversize valve guides".
http://www.yearone.com/infocenter.asp?icl=1&iclURL=updatedsinglepages/Id_info/engine_id.asp

Troy

[68ChargerJMP]

Well, nothing special huh?  Thanx.