Hauled 20k with no problems and 3.55 gear! Hauled it where? Across the street.I've had 3.55s it is far from a pulling gear.If any speed lost on the interstate hills it will never be regained towing 8k up unless falling off a mountain or running WFO and hope no one forces you to slow down on a big incline.I got tired of driving like a loaded low horse over the road rig.D.C. wanted the 3.55 gear gone back in 98/99 just couldn't do it then with Dana.I bought my truck to tow with.3.73s never entered my mind.If I want to drive 70 plus mph non towing I have other vehicles for that.

 

Horses, cattle, utility trailers, feed and minerals , cars, palm trees and many other various and sundary things from Ocachobbee, Fla; to Richmond, Va; LaFayett, LA and many places in between. Never had a problem with 3.55's and a 5 spd other tha 5th gear would not stay put until we made a jam-nnut to go on it.

 

My race rig is only around 8500, but I love my 3.55 gears. Kind of wanting the best of both worlds is a fine line to walk. Good mpg at highway speeds, lower rpms for better mpg at those higher speeds.....yet the power to maintain speeds with the trailer in tow and keeping it at a "happy" rpm. By the way my truck was born with 4.10's. I changed them to 3.55 within 6 mos. of buying the truck.

 

The ones I had I changed from 3.55 to 4.10s.LOL 3.55s sucked towing more then then 5k any distance.Mty neighbor has 3.73 in his 05 dually.Says they were a mistake also.Its not in the engines sweet spot towing any weight unless towing above 70 mph which he does not like to do.Also on large inclines with curvy roads its eaither too fast or lugs,downshifts and engine screams.I never considered fuel mpg as a key point on my truck purchase.Towing was my key concern.My Gran Marguis gets mid 20s at 75 mph.I have never used my diesels as everday commuters.

 

Go with the 3.55, you can alway shift down on the real steep stuff. I'm towing with only 4 gears, no wicked low first and second gears. No extra overdrive gears. 4.10's would drive me crazy, you would be shifting non stop, then just max rpm at 90mph area.

 

Depends on where you tow at, the nasty stuff demands 4:10 gearing. I think for most towing the higher gearing would work just fine though. Everyone has to remember these engines do not "need" to be shifted until 1600rpm. Do you understand how lazy that is compared to the alternative?

 

To EACH HIS OWN I reccon

 

I had 3.55's on my 02 but I ran 35" tires. I went to 4.10's and was much happier, but I only towed with my 02. Mileage was a little off compared to the 3.55's but towing at 60mph was around 1400 rpms and that produced alot of smoke. With the 07 six speed the key is running below 2000rpms. Keeping it under 65 netted me 16.5 mpg. Running 70 was 13ish and 75 was horrible. In the 11's. Now with the gear vendors OD, I can cruise at 75 and get high 16's cruising at 1750 rpms. 70 mph gives me right at 18.5 average. That is where I cruise. I had horrible mileage at first with my cruising speed, just have to know that the faster you go, the worse it gets. Now for towing, this is an awesome combination. The camper makes the truck work, but the gearing and the tranny work great. So far, only 3200 miles, but I love the truck.

 

you put an external OD on your 6spd?
I like the idea just don't want to part with the cash .

 

this is my 1st 6 speed and the clutch is easier than my partners 04 clutch. i run the mountains alot. always in the gas and out of it. i average 16.5, 06' megacab 4x4, 35" toyo's, attitude and a pacbrake. 5k on it

 

I have had 2 6 speeds now first one was on a 3500 DRW 2X and I was consitently getting right about 20 MPG with it. Can't imagine you would want one of the autos they offer with these trucks.

 

I have had two as well an 02 and a 04 but this 07 is differnt the final ratio is lower so now at 70 mph the engine is turning close to 2300 rpm's

 

I think you need closer to 20,000 than 10,000 to break in. I am getting over 20 MPG onmy 2006 Mega 2500 4x4 6spd. I drive easy - under 65 and coast. I also have 34inch tires which llok good and lowermy RPM.

 

I love mine hauled 17,000lb in hay friday and it pulled like a champ.

 

NO I think you all are missing the point if the engine is turning faster so there for it is firing more so more than likely it will use more fuel providing it is not being lugged. Yes i know it needs more miles but most of you people dont drive your trucks enough to do that. I generally put close to 10000 miles a month on a truck so thats over a 100k a year so if i loose 2 miles a gallon over 2 years thats usually the amount of time i keep a truck so that is a chunk of change and thats why im pi--ed off about