I custom ordered a HD2500 Sierra SLT heavy spring and tow pkg, loaded and then some, 6.0L w4.10 gears. I like it for what I'm towing 242 Formula. If I had it to do over...((( GET THE 8.1L )))
The difference in mileage is minimal but the difference in power is HUGE.

EXACTLY !!!

the dmax is great do not buy one if you are not going to put 20K per year on

i have pulled my formula 353 with all combo's. the 353 on trailer weighs 11 -12 K. the 6.0 worked really hard to get it dun, 7 - 8 mpg.
8.1 purred like a lion 9 mpg and could use cruise (could not on 6.0)

duramax loved the load.

the denali will move the load but not like it over long distance.

these are my experiences also towing a 353.
12K plus on an Eagle with fuel
the 8.1 makes much more torque where it counts than the old BB

the DMax just doesn't sweat it!

wondering how you guys got 8.1 trucks with 4.10 gears since they were only ever available with 3.73's I have a 2002 2500 HD and tried to order it with 4.10 's and they aren't available that way .what does your gear code say on the tag in the glove box? starts with a G

GT4 is 3.73.
GT5 is 4.10.

The Avalanche has a factory option for which set you want.

I have a 2001 Chevy 2500 HD with 8.1 and I agree with everybody else. I get about 10-12 normal around town. I have gotten close to 16 on the highway not towing of course.

I have a 2004 regular cab 2500HD 8.1 Allison and I looked at the code GT5 and have the window sticker that says 4.10

Cordell

the 8.1 was available with both ratios from the get go.

you CANNOT get a DMax with 4.10's

4.10 standard with the 6.0 to try and make up for torque it doesn't have.

perhaps you were taking the word of a less than knowledgable dealer?

Does anyone know how the 07 Suburban will look like? Or is there a link to a site.