Once you see a wreck after someone towing anything at that speed you might think twice about being in a hurry.There are other people on the road you know,

 

Last year I towed a 15,000lb load from california to Louisiana. When i wasn't in the montains I averaged 12 mpg at 70-75. Thats towing over some big hills in arizona. new mexico and texas also. When I went through some mountains in Californian with 5-6% grades I was GLAD I had 4.10 gears. When I'm empty I get 21 mpg driving 70. 3.73's won't make much difference from what I've seen from other owners in gas mileage. It's just a bit noiser due to the revs if you drive fast. It's kind of like that old saying, "better to have and not need than to need and not have". Your engine wont lug as much with 4.10's. I dont tow much either but I'm gald I have the 4.10 gears. If you REALLY dont like the 4.10's you can always get a set of 3.73's installed for about $500.

My 2 cents

 

Exactly, 80mph in a 4.10 truck is like 2700rpm. So as long as you stay below 70, the 4.10 is the way to go. If you drive all highway miles at 80+, you'll want the 3.73's (and some taller tires for approx 3.55).

 

I decided to get the 3.73 gears. Based on everyone's comments, it seems that both the 3.73 and the 4.10 have their advantages. I decided on the 3.73 given the price of fuel. The 3.73 should (I hope) give a little better fuel mileage, expecially when not towing. The 4.10 "might" give better mileage towing depending on the wind resistance and weight of the load. I feel that the 4.10 would probably have more acceleration and be more driveable when towing but given that I only tow about 30% of the time I went with the 3.73 which "hopefully" will provide better fuel mileage. Thanks again for all the thoughtful comments.

 

I have about 400 miles on my new CTD 05 truck and i opted for the 4.10's with the six speed i hit a max speed at 90mph unloaded at redline. I ordered the 4.10's for when i go to bigger tires and also for the extra acceleration which is cool... i can lug a taller gear longer so less shifting too. for what its worth my mileage on the OH sees about 15.3 mpg and my truck isnt broken in yet. i do dislike the limited speed though as i drive 75-80 unloaded.
Actually the gears are probablly keeping me ticket free!