I just took delivery on my 04 Silverado yesterday. It has the Duramax Diesel 6600 engine with the 5 speed Allison. I see posting referring to the Duramax LLY. Is this what I have? The unit was manufactured in March of 04. Also, how do I know if I have the Second Generation 2004.5 or not? I see references to that posted often. Thanks. Any info. would help.