Proper gearing

Look at the trip meter, I was only 12 miles into that tank of fuel. Lol.

 

2017 Int. I am 1475 at 66.

 

I like that. That truck gauges tell me shes doing well with potential to deal with the little hills around the area there.

Dump trucks are not supposed to be FAST or Trying to... be top end running. You could horsewhip any old dump to whatever you like.

I strongly suggest the tall tires. That will help a little. When you are getting into changing rears don't go below say 3.65 at most. You need that get down and pull stump gearing back there.

Another option would be to put on a overdrive box behind the transmission. I don't know if it's possible in big trucks. But one of my cars (A El Camino notorious for reelly extreme ration in the drive axle had one for highway work. Even though the engine was only like a 305 under a Carter carb she pretty much maxes out top end around 100 flat. But you are all wound out to get to and stay there. 70 going onto the interstate is gulping fuel. But you can load the car with 600 pounds of stuff and go. She will do that much at least.

I best stop here, I feel chatty today and that's not very good sometimes.

As a parting shot, I love the gauge picture, it's good and tasteful. But would imagine those silver rings would be a problem when the sun comes in off the drivers window sometimes. (Ive always had trouble with that, it's just one of those life time things when the eyes burn in dots from concentrated sun.)

 

I suggest changing transmisson AND rear diffs. 13 speed single or double overdrive with 3.09 or 2.94 rears. You will have plenty of choices running loaded and can idle down the road running mty for another load.

 

The cost of changing rears simply for the sake of economy will take a long time to break even. Now if your rears are high mileage or one blows that's another story.

 

Rears are and all ways have been a pricey item. That’s why auxiliary boxes were so popular. Get low and high gears in one setup.

I may be going back to the auxiliary box. 5 and 4 in one truck and 13 and 3/4 in the other. Let you know what I think.

 

You won’t notice much difference going from 3.90 to 3.70.