Gentlemen,
I'm new to the Duramax coalition and the Diesel Place. What a great info forum you guys have going!
Please pardon my ignorance but I need to know. . .What is a "2004.5" Duramax and how do you know if that is what yours is?
I took delivery of my '05 Durmax in August of 2004, production date on the door sticker is 07/04. Is this actually a 2004.5? Or would it actually be labeled as a 2004.5 and I'm just a dork?
Best regards

best way to check is to run the Vin number.. I purchased my 04.5 in August of last year as well.

the 04.5 is basically when they switched over to the new LLY motor and dropped the LB7. The Vin number dictates which you have. I think its the 8th digit..if its a 1 its an LB7, if its a 2 its an LLY. This is only for 04-04.5 models. The 05's are LLY period.

Your truck is considered a 2004 if it is a 2004 model with the LB7 engine.

Your truck is considered a 2004.5 if it is a 2004 model with the LLY engine.

To my knowledge, a 2004.5 is not labled as such anywhere on the truck.

A 2005 is a 2005 period and it will have the LLY motor.

My 2004.5 was manufactured in June of 2004. I believe July is when the next model year trucks are produced.

You have an LLY. Mine is a '04.5 and was built on 01/04. I'm not sure when they did the cut over to start building the '05's. Did you get a window sticker for your truck? It should say at least if it is an '04 or '05. If it says '04 then it is a '04.5 going by your build date. If you don't have the window sticker do what braino said and have the VIN number checked.

Gentlemen,
Thank you! It was sold as an '05 to me and Briano's vin# description indicates a 2 for the LLY. Thanks again! :)

The cut off date for LB7 engines was a truck build date of Dec 31 2003 or before.
All trucks built after Jan 1 2004 have the LLY engine.

I believe another way to check is to look at the SPID label stuck inside the glovebox door. The engine option code should be there amongst the other options. LLY or LB7.