That 8.1 won't get 12mpg unless you push it!!

 

Some interesting posts.Well I towed 10k with 3.54 gears and IT KNEW it was back there.Going from Georgia to Nebraska on interstate some hills was gutting it.That was with a somewhat modified engine(injectors,turbo housing,exhaust etc.)Was a real stran starting off on large inclines also.My next mod to that truck was 4.10s and took care of that.3.54/3.55 gears in my opinion are NOT pulling gears,there toting HIWAY gears.My neighbor tows a 3 horse alum.gooseneck horse trailer 90% of the time loaded with a 05 48re 4x4.He says 3.73 were a MISTAKE.Should have gottion 4.10s.Says 3.73 are ok on the flats but going through W.Va on up into Ohio etc.he's hard into the throttle to maintain speed.He rides with me in mine pulling 10k and comments about how little effort mines pulls it compared to his.Now towing 4k or so I'm sure it tows it with no problem.But get in the 7k to 12k range a truck needs 4.10s if its to hold up for mile after mile.Just my 02 worth.

 

Right on Houndog.

 

My rig tows 8,000 lbs 75mph up and over any mountain Wisconsin has thrown at it with 4.10's and an EZ on 4. Otherwise completely stock.

Andy

 

Not to flame anyone but a few posts sound like MY truck gets 30mpg and 21 towing with no problems.I hated 3.55s towing.Felt like I was pulling again with a gasser.Mash it up the hill,back off down the hill.Was a chore to drive long distance.Truck I have now I set the cruise at 68 or so and even 4% inclines it stays in 6th gear.On less inclines it maintains the same speed up the hill and down the hill without a whole lot of effort.Much nicer driving experience towing long distance.A lot less tiring on me.

 

The guy is looking at a 3rd gen truck so 3.54/3.55's are not an issue. Go 3.73's if you are only going to tow light. A 4K trailer will feel about the same as a half ton gasser with a 50lb bag of dog food in the back. You won't even know it's there.

 

Lets not forget that the trailor is only 4000 thats like using a trackhoe to pull out a rose bush

 

3.73 with a 38 " tall tire is the equivalent of a 3.09 ratio. To maintain the 3.73 ratio you need to buy the truck with a 4.5 ish ratio, which is not available. I assumed the truck came with the 265/70-17's.

 

buster (the thread starter) owns a Auto transmission. Y'all with manuals - there is no doubt that a manual and 4:10 gears is the ultimate tow vehicle. BUT, it is a different animal when you have an auto tranny. I say again, my last rig had auto, 4:10 grears and 35" tires. New rig has auto, 3:73's, and 35" tires. The higher gear truck is a superior tow vehicle. Same trailer, same routes, higher speeds up grades and cooler running engine. It's all in the way the computer is programed.

 

They make 4.56 gears for our truck.

 

A couple of posts here hit the nail right on the head. If you're not towing heavy, or if you're not towing in a lot of hills, the 3:73's are the way to go, even with bigger tires. I'm like Buster, I rarely tow over 4k, and it's pretty flat here in AZ. At least the trip from Phoenix to the Dunes just past Yuma is. I'm running 315/70/17's with 3:73's and 48RE, 75-80 mph (yes, it's recalibrated), is just at 1900-2000 rpm with that combo, and i get a consistent 15mpg with that load at that speed (TSB 18-037-004 done). With 4:10's, that speed will have me spinning a little higher than I want. The truck has yet to drop out of OD at this speed with this combo, it never feels like it geared too tall and passing power is awesome, even pulling the trailer. I'd do it again the same way in a heartbeat.

My previous truck was a V10 Superduty with 315/75/16's and 3:73's, it there were even just a whiff of a headwind or the slightest grade it'd drop out of OD, sometimes even into 3rd or even 2nd gear, nothing like you engine suddenly screaming at 5000 rpm do wake you up! I'd be luck to get 8mpg on the same trip. The diesel's a whole different animal.

 

I have a 4:10 gear in mine. I get about 16.5 mpg around town and about 18 mpg highway and that is running at about 75 mph. I like the ratio because I think it is easier on the transmission (48re). My $ .02 worth

 

I've ben toying with the idea of changing gears myelf and have been torn between 4.10 and 3.73. I deliver trailers in the summer time with my truck and with the 3.55 and the 315s i know those trailers are back there epecially with a couple of the grades bwtween los angeles and las vegas. couple of them I'm in 4th but still pullin the grades @ 65mph. After reading this post and all the different opinions I'm still undecided. I honestly think that the 3.73 would be the way to go for an all around do it all gear ratio.

 

Don't think a DANA in 2002 had a 3.73 option.Only 3.55 or 4.10

 

It seems most of you fail to realize you can regear your axles

For the AAM axles they make 4.56 gears. My truck came with 3.73's, and I have 4.10's in it now...