Im going to look at an 04 Duramax in a few mins, the sticker on the door says built 01/04. Is that an LB7 truck? Just wondering, thanks..........

Should be LLY. Check the serial #. If 8th digit is 1 it is an LB7. 2=LLY

thanks, when i get under the truck to look at it, what part of the block is the serial number located?

Just look at the vin number....either on the door or the tag you see when you look through the windshield on the driver's side...

Just look at the vin number....either on the door or the tag you see when you look through the windshield on the driver's side...
oh ok, last two numbers in VIN are "22" so guess it's an LLY. Is that a good thing or bad thing? What differintiates the two? (as i go to the forum search function right now)

The EIGHTH number from the left, not the last two. It's also the THIRD number from the left after the series of letters. LLY's began in 2004.5 model year, so it's very possible that you have an LB7. Another quick check is the valve covers. If your injector lines go into the center of the valve cover with a rubber grommet, you are an LB7.

VIN Code
1 Country of origin (US -1)
2 Manufacturer (G -General Motors)
3 Make (C -Chevrolet Truck)
4 GVWR/Brake System (H -9001-10000/Hydraulic)
5 Truck Line/Chassis Type (K -Convential Cab/4x4)
6 Series (2 -3/4 Ton)
7 Body Type (9 -Extended Cab)
8 Motor (1 -LB7 2-LLY)
9 Check Digit
10 Model Year
11 Plant Location
12-17 Plant Sequence Number

My VIN is: 1GCHK29131Exxxxxx

here is the VIN, let me decifer it:

1GTHK23254F186322

thats an lly.

thats an lly.
in your opinion, good thing or bad thing or no difference? Still searching for the differences between the two:o:

1GTHK23254F186322

Yep it's an LLY!

Also, United States Origin, General Motors, GMC Truck, 9001-10000 GVWR/hydraulic brake, Conventional Cab/4x4, 3/4 Ton, Four Door Cab/Utility, LLY, 2004, and originated in the Flint Plant.

Idle, I love the way you explained it. I'm sure even Hellen Keller would understand):h

The LLY is the newer version with a variable vane turbo rated I believe at 55 lb/ft more of torque than the earlier LB7. There are advantages to both. The LB7 has a lot of tuning milage already logged for your own good while LLY with its upgrades is a newer learning experience. Niether one is bad the but the LBZ is no longer offered in the pick-em-up trucks. Welcome to the club and enjoy that LLY to its fullest potential.