I've picked up a 1996 3500 dually with a 14 bolt and a 4.10 rear gear. The thing hauls my trailer like a bull but gets 10mpg doing it. Try to drive 75-80mph on the Chicago highways and the engine is just screaming. At that speed it will only get 11mpg running without the trailer. I'd like to maybe do some junkyard prowling and see if I can find a rear end with a tall gear but was wondering if anyone else has had any experience with the longer ratios? I'd like to know what sppeds you drive and what mileage you get, also how well your vehicle tows a trailer.
Thanks!
Chris

I have 3.73 and average 17 mixed and 20-ish highway at about 70-75. Can't say how it does towing or what the RPM's are at, but it just happily humms along and didn't even feel 3K. You can't really expect the same mileage as me though since you have a one ton DRW where I have a half ton SRW. Shouldn't be too awefully lower though.

Is it an auto or manual? I have a 98 with a 5 speed and it gets 17-18 MPG runnin about the same speeds on the highway unloaded. Couldn't tell you what it is loaded but it has a 4.10 gear in it too.

Here is a link (http://www.darkside.ca/tool.asp#8) to help determine your optimum tire size for a given speed, and also on this page is a rear end ratio calculator. If you can't figure it out, give me the specs on your tires and the speed you like to drive down the highway, and I will figure out what rear end ratio you would need to be at 1800 RPM.

Sometimes though, it takes a tire size change too if you want to get it just right.

I have an automatic. 1850RPM equalls about 55mph. As speed increases, rpm skyrockets. By 80mph, the tach is around 25-2600 and the motor is screaming. I suppose I'd get good mileage if I drove 55, but in Chicago you could get run over at that speed.

A gear vendor overdrive could give you the best of both at a price.

Id like to drive a 6.5 burb with 4.10s in it to see what the power is like and the mileage. Mine has 3.42s and the mileage is 13 in town 20 highway no load. (I've seen 22 before but not after my turbo-master, could be better with new timing chain, injectors, and exhaust and my small fuel leak fixed).

I think if you are making only 10mpg, even tho youre in a 1 ton with 4.10s and a load, that you should be making better mileage.

I had 4.10 gears in my old Suburban with the 6.2. It pulled just about anything I could hook to it, although not very fast.

I now have 3.73 gears, which I consider a good compromise in mileage/performance.
The engine runs slower and quieter, although my mileage is only 15 city/16.5 highway. I babied it on my last trip by driving a steady 60 mph. I got 16.5 mpg. Maybe my 18:1 compression ratio affects it.

In a heavier vehicle like the DRW pickup, the 3.73 is going to seriously hurt your towing. I tow up to 6,000# once in a while with no difficulty. It really depends on what you tow. Don't expect to get a payback on the ratio swap. Do the math and it will take years to break even on the swap. Your engine will probably last longer with a 3.73, assuming you don't get to happy with the throttle when it doesn't accelerate like it used to.

Jake

i'm not sure what my exact mileage is but it sucks compared to my burb lol...not horrible though, i don't expect much out of a 3500 cc lb :p:

I have a 96 ECLB DRW and get about the same mileage although alot of people claim to get much better with the same/similar truck. I still have a few things that I am going to do that should improve it. I don't know how old the injectors are, so I will be replacing those(probably), and I still have the factory exhaust with the mileage limiting soot trap. Once I do those, I'll see if my mileage increases. Then if I ever go and pick it up, I am going to have a 3.73 rear to install, and may try that. I just have to wait until the snow banks in my driveway are gone so that I can get my trailer out and pick up the sheel it is bolted to. Oh, and I'd like some warmer weather too, since the dually is parked for the salt season, and doesn't fit well in the garage.
So, I should have some answers for you in about 6 months. Maybe longer if it keeps snowing.

Id like to drive a 6.5 burb with 4.10s in it to see what the power is like and the mileage. Mine has 3.42s and the mileage is 13 in town 20 highway no load. (I've seen 22 before but not after my turbo-master, could be better with new timing chain, injectors, and exhaust and my small fuel leak fixed).

I think if you are making only 10mpg, even tho youre in a 1 ton with 4.10s and a load, that you should be making better mileage.

MY 98 Burb has 4:10s, is a two wheel drive and gets 19-20 mpg. But you have to keep it at 65 or under otherwise the mileage goes to hell in a handbasket.
My truck CCLB is two wheel drive as well, 4:10s and averages 17.5 mpg consistently.
You just can't go fast, but Chicago being what it is, you really don't have a choice.

See? Ghostrider is one of those people that I was talking about. His Crew Cab and my dually should weigh about the same. That leads me to believe that I have to do some maintenance to mine to get the mileage up, and that there is actually hope for bigger numbers. You can probably benefit too. After I do that stuff, then I will try a different ratio.

I have a 96 ECLB DRW and get about the same mileage although alot of people claim to get much better with the same/similar truck.

So, I should have some answers for you in about 6 months. Maybe longer if it keeps snowing.
Interesting. Man, not only do we both have 96 moedels, your truck is even the same color as mine! I've got all that cowboy pimp Lund stuff and mine's a Chevy though. I love that Jade green metallic paint. I've developed a truck washing addiction.

well.. another one for your comparison,

i have a 99 4x4 dually, i just recently made a trip from VA back to NY, empty ofcoarse, with a really topped off tank (till the cap:) ) i made it just past 500 miles on a single tank, i would safely say about 530-535 miles, average 65, cruising between 60-70 and i if remember correctly, my rpm's were at about 2200-2300 and climbed up 200-300rpm, till 70mph.. i calculated for speedo error as well as compare to my GPS that i had with me, and i have a 4.10 LSD in the back.. and that was with the stock 225', now im running 235', and that dropped my rpm about 100 at the same speed

so... 530 miles / 31 gallons = 17.10 to the gallon..

30.6 gallons was what it took to the same fill level, to the cap :)

My 3500 has been a hair over 15 mpg a few times in combined city and hwy, it's at and slightly over 10,000lb too. I usually don't go over 62 mph tho' ! (and one of those 15.1's included a trip of 60-70 miles at 55 mph. )

Interesting. Man, not only do we both have 96 moedels, your truck is even the same color as mine! I've got all that cowboy pimp Lund stuff and mine's a Chevy though. I love that Jade green metallic paint. I've developed a truck washing addiction.
Well, then I'd have to say that you have a nice truck. I was just looking at trucks to get an idea on price, then I saw this one, and it was green, the same color as my enclosed car trailer. I bid on it, and won the auction. Now I'm looking for a green golf cart to match. I love driving it but parked it for the winter. Now I'm having diesel withdrawal, but I think Spring is close, so I can wait.

I love driving it but parked it for the winter. Now I'm having diesel withdrawal, but I think Spring is close, so I can wait.

So what do you drive for the winter?

I drive another GM truck, the 88 gasser in my sig.
I miss driving the diesel, but when I bought it, I did one of those checks on it, and every entry said Florida except for the last one that said Maine. The underside of the truck looks nothing like the rest of my "fleet". It wasn't rusting and flaking away. I decided to keep this one parked when the salt hits the roads. Massachusetts isn't nice to vehicles in the Winter.

can't remember who it is, but he has 1500 dailydriver. he went to put 3.42 in but got 3.21 and i think runs 31inch street tires. if you had SRW i would think locate 3.08 axle and swap out to see. that way you didn't invest alot. depends on how often and how much you tow. seems 3.42 lowest for any towing, to keep engine in torque range.

What do you tow, how heavy, how fast and how often? If you tow 15k half the time stay with the 4.10's, if you only tow 15k ten miles a year put what ever you want in there. For interstate towing I like 4.10's(OD) or 3.42's(direct), 3.73 your kinda in between the gear you need if you have a heavey load. My 92 3.42 truck is a 5sp though, I could hold whatever gear I wanted and its a mechanical engine so I dont know how it would work in a auto/electronic truck.

I like my 3.21's(used to be 4.10) in my 93auto(mechanical IP) daily driver, but I drive fast, I think most people would like 3.42's better. It's gotten 19's on longer trips running 75-85mph.

Normally day going back in forth to work in the 93, I let it idle about ten minutes before leaving the house, I drive it running 70-?(speedo only goes to 85), 30 miles each way(no babying it, I drive it hard, passing, jack rabbit starts, ect.), once at work there is normally a 30min wait in line idling getting in and 15-30min in line getting out, it usually gets low to mid 14mpg's(highest I've seen was low 15's and lowest was low 13's, IIRC).

I'd say if you spend half your time driving at, 75mph get 3.21's, 70mph 3.42's and 65 3.73's would get you the best mpg's/driveability. If you fight stop ang go traffic for 45min and drive 75mph for 15min out of an hour, you might be best with what you have or little mpg gains(just a quieter engine) with a gear swap.