GM 6.6 & 3:73

Before I can answer, are your talking 6.6 Gas or 6.6 Duramax Diesel????????
Will make a huge difference in the answers you get.

My 05 duramax ,3:73,towing a 28’ TT about 6000lbs, mostly from Ohio to eastern shore of Maryland via Interstate 68 averaged about 12mpg. But I don’t get in any hurry going anywhere(speed limit or less)

Michelle.S wrote:
Before I can answer, are your talking 6.6 Gas or 6.6 Duramax Diesel????????
Will make a huge difference in the answers you get.

sorry, I just updated my post, Gas.

Then sorry can't help. Last gasser I had was a 1987 Silverado 1500 with the 350/5.7 On my third Duramax 2005, 2011, and current 2018 pulling three different Fifth Wheels, but very close to the same mileage with all combinations.

OP, you might want to add some info on what you plan to tow. I towed an 8-9000lb TT with a GM 8.1 gasser back ~15yrs ago. It pulled well (except up steep grades in Rockies) and never passed a gas station without stopping. Pulled 14-17k 5ers the last 10yrs with diesels…no comparison.

They're slightly better than a 6.0/6 speed/4.10 truck.
The lose some of the new power to the taller gear ratio and obviously the trans isn't adding anything to the equation.

Milquetoast offering for a "new" high dollar HD truck. Both the Godzilla 10 speed and Hemi 8 speed out pull it.

Towing a fifth wheel, GVWR at 14K. I am just looking at comparisons on what others had from gas to gas, more specifically the change form the 6.0 to the 6.6, gas yes, 4:10 or 3:73, Preferably the 3:73. Just getting some real life info. not opinions. thanks

I had a 2020 6.6 gas reg cab dually. I towed 15k lbs (gooseneck with round hay bales) many times. It was in Michigan. No issues, and had experienced some uphills from a stop.

jffnkrn wrote:
Looking for actual input, experience not opinions without experience.
Anyone that has a GM, 6.6 gas with 373 gears, towing I would like to know your experience with towing power, fuel mileage and overall performance.
Again, looking for actual information and maybe a comparison to what you had before. thanks in advance. Jeff

Sorry no experience, just opinion.
Towing 14K with a gas 3500 SRW, you will have plenty of payload, and I assume Peoria it the one in Illinois, as long as you stay in the plains states pulling should not be an issue.
If you travel to either coast that 6.6 may need to rev a bit in the hills, but it will get you there.

Actually Peoria, Arizona. Hills normally to get me out of the valley to anywhere, been over a few big ones in the past, Wolf Creek Pass and can't remember the other one east of Yellowstone,plus a couple more, california through oregon etc, Nevada, utah etc. but with 6.0 and 3:7 3 gas, slow and struggled some but overall did well. thanks