What is the difference in fuel mileage? How hard and how expensive is it to change them out? Which gears are better overall?

 

I have heard 1-2 MPG difference. It kind of depends on the towing you do as to whether to get 3.54s or 4.10s. I have 3.54's in my 99 and have no problem towing 7-8K in OD with my slushbox. I don't tow all the time so 3.54 gears are better for me than 4.10s. If I was towing my GCVW limit all the time I'd probably rather have the 4.10s.<br>I'm no authority, and this may be why I don't see the point of gearing down a diesel, since the diesel was made for low RPM torque.<br><br>Chris

 

bolo2,<br><br>What kind of driving do you do?<br><br>I have 4.10s and think that its probably the best gear for what I do. My truck is used as a delivery truck. Lots of stop and go with 3000+ lbs in the bed. I average 17.5 mpg with the mixed driving I do. Not sure about the hi-way mileage. The only time my truck has been out of the city was to go to the in-laws that are 200 miles away. I got 23 mpg. That trip included 2 Colorado mountain passes.<br><br>

 

I have never seen fuel mileage over 18. I usually get 15-16. I don't see mylself pulling more than 10,000lbs. I just want to cruise at 75 - 80 without running such high rpm's.

 

How many miles on the truck?

 

33,000 miles, change air and fuel filters on every other oil change. Change oil every 6000-7000 miles.

 

Should be broke in.<br><br>Have you ever towed with it?

 

1-2 mpg differance<br>not to hard with the proper tools and knowledge<br>400-600 per axle<br>I'd stick with Dana gears<br><br>would be cheaper to run taller tires.

 

I second the taller tires. I have the 354's., and I have never had any trouble towing.<br>USE THAT TORQUE!

 

I have 3.54's, get around 16 mpg regularly. Never checked when towing but never have had a problem getting up &amp; goin.

 

I have 4.10's. Above 65 I notice a drop in mileage, 75 costs me 4-5 mpg over 60mph. That is on long trips. I love them around town and towing, even though my friends that I have let drive my truck about having to shift so much. IMHO if you are going to drive above for a long distance get 3.55's. But I will buy 4.10's again ;D

 

My 3500 gets 16.5-18.0 tooling around empty, and 13.5-15.0 when pullin hard. Around 2000 is where it likes to run.

 

I have almost 8000 miles on my rig and I average 17 city and 22-23 highway (75) not towing. My trailer weighs about 3500 lbs, and dosn't really change when I tow it.<br><br>I do love the 4.10s!!

 

I never had a problem pulling with th e 3.55's either. Now that I put on the 35's, I can tell that the truck is working harder. What I will probably do is get the US gear splitter and get the underdrive. My fuel economy empty right now is better as I run 2000r's at 80. I think if I still had the stock tires on the equivelant gear would be a 3.08. The US gear would make the truck pull the r's alittle better when pulling 10k. Im not saying that it doesnt have the power, I am just saying that I can tell the difference in power. If you are keeping the 33's you have on now, you are running an equivelant 3.73 roughly if you still had the stock tire on, and that is the gear I wish I had.