Mine was a LBZ so thereisn't much of a power difference,Smitty

the 06 lly engine was actually a lbz with detuned programing in the computer. The reason some were released with this programing was the lack of availability of the new torque converter for the 6 speed allison, and they made the decision to limit the engine with programing . Internaly it was the same engine as a lbz

Nice!!!! We'll have to take our trucks to the strip this spring and line 'um up, my LBZ vs. that LMM.............God Knows that Pontiac won't be done!:evilb: What did you run in that 04.....14.50? Can't remember.

The 04 ran 14.97 with old style pre -lly duramax,never ran the LBZ-06 down the strip. Lets put our boats behind our trucks and run-em off out front of my house:grinser010:,Smitty

You got that right. I'm a GM man died in the wool but I'm gonna keep driving my older body style until they build a better looking version or I might change brands. I check my mileage every tank on my duramax and I get just under 18 mpg religiously in all kinds of everyday driving, and get 9.5 pulling a 38' boat on the interstate at 75 mph on mostly flat ground. I don't think the 08's with the new emissions will get anywhere near that.

I agree...I'm a huge Chevy fan but the front of the Chevy HD with those big chrome (plastic) corner boxes are more than I can take....they should have at least made them open up to be used as tool boxes or as beer coolers or something!:(

I will say, the GMC is much better looking and is what I would have to buy.

Fuel mileage
 

Just took delivery of 08 GMC 2500 HD with the LMM engine in it. My old 04 GMC would get 18.2 mpg on the highway at 75 mph. The new one is getting only 16.5 mpg. Now it only has 3500 miles on it but I was hoping with the extra overdrive that the mileage would be better. We are leaving to go to Florida this week so I will see if it improves as we go. But for now I am a little disappointed. I think the old one had that burst of power traveling at 75 then the new one as it seems a little sluggish when you punch it. I think this is mainly do to the overdrive now.
The other thing is the hood you can't see over the right side to judge your distance. The old style Serria Classic had better lines. They should have put the bigger motor and transmission in the old style they would have had a awesome truck.

I actually liked the looks of my 04 much better than my 06 (other than the cool duramax/allison badges). The 08 ltz's (like the one I just got) with the 17" rims and 265 tires have a much better look then the regular ones with 16" rims. The gmc versions look like fords,I like the hood lines of my new 08 but the body lines do bear resemblence to a frickkin toyota. The 12 way power leather seats are the best thing about the truck,they actually recline far enough to sleep while someone else drives (unlike my last truck),Smitty

A co-worker just bought a 08 gmc,it has bezels on the gauges (my ltz chevy doesn't) that give it a buick sedan dash look,I didn't care for that plus the door armrest are different and jut out right where my left knee rest while driving.We been ragging on him at work that it looks like a super duty ford for past week since he got it too:evilb:,Smitty

I'm a Chevy guy too, but the GMC is definatly a better looking truck. I won't be buying till March or April, so I'll have time to consider both.