Hamboner got it half right. Cost, weight are two big reasons.

But the biggest is efficiency. I would NOT spec a 10 speed overdrive, I'd rather just go with a 13 speed (they're all overdrive).

That specific ultrashift, or the I-shift are both direct drive. Saving about 2-3% in fuel. That's a lot of dough.

All Schneider trucks are direct drive.

Here's what I said on another forum, explaining the specs in more detail:

Like i always said if you cant make money with a hood then you got some real problems.

I just don't get it and I would really like to understand it. I always thought an overdrive was better, get the motor spinning slower at higher road speed. Slower is better right? I am spec'ing a new truck right now and I have preliminarily selected an 18 speed, but am open to ideas especially if I can save 2-3%. I already do 7.5mpg with a 13 and c-15 with 3.73 and 24.5's.

In todays fuel market I believe in doing anything to increase my MPG and nothing is off the table.

What you want to do is have a direct drive with a certain gearset that allows the same overall gearing as a regular transmission.

I'll explain:

Truck one, 10 speed direct drive, 2.64's

Truck two, 10 speed overdrive, 3.55's

These trucks have the same tires. Every gear will be within 1% of each other(overall ratio) and the cruise rpms will be the same. You're giving up gearing at the diffs, but you have more at the transmission.

The two advantages are:

1) Power is going direct through the transmission. No power is going through the two countershafts, then back to the output shaft. It is going STRAIGHT through.

2) Nearly everything is spinning slower, back half of the transmission, all the driveshafts, etc.. This lowers losses as well.

The trick is finding a combo that will work for you. If you're hauling more then 80,000 lbs, no go, because there's no direct drive transmission rated for that. Going fast? Again no go, because even 2.64s have too much gearing for going fast(never mind 2.79 or 2.93's). Play in the mud a lot? Not a good idea, because the driveshaft is seeing about 33% more torque.

Basically if you want to do a direct drive setup with efficient tires, you cannot go fast at all, as seen by the chart I posted above. Sure one could go with 11r22.5's, lo pro 24.5's or 11r24.5's but those tires are not as efficient, XDA energy tires are also only available in lo pro 22.5. Super singles are the same diameter as lo pro 22.5's.

Says the company driver staring at a dogs butt all day :lol:

I admit I do have a hood but if I could save 1mpg without one I would do it without even thinking about it for a second(for the next truck). Think about it...

100,000 miles at 5mpg=20,000 gallons@$4.25=$85,000
100,000 miles at 6mpg=16,666 gallons@$4.25=$70,830

Straight to your pocket savings of $14,170.

Thats why everything I do behind the wheel is done for improving my MPG.

Wow each 1/10th is worth 1400 a year.

Never thought about it that way, kinda makes me feel better as I motor down the highway at 60 in a 65 with swift passing me.

My mileage went up 5/10's in the last month. Now that I'm able to use some downhill momentum to climb the next hill without blowing tires off. Before I had to ride my jake all the way down to keep my speed under 60mph, as soon as I went over 60 for more than 10 minutes,...off came a cap.
My IFTA says I averaged 7.9mpg for the last quarter, which should be fairly accurate since I idled only 25 hrs during that quarter.
I only idled 5 nights the entire winter, I spent less than $100.00 on propane to keep my truck between 65 and 75 degrees, and that also included always having hot water and the stove.
If I had idled it would have cost me over $3,000.00 in fuel,...instead it only cost me $100.00 and if I add the propane unit,tanks, regulators,hoses,..the entire set up cost around $350.00, so thats a whole $450.00 to keep my truck warm all winter, and I was OTR the entire winter, and I used the propane heater all the time the engine was off.
This time out I'll have opened my exhaust up by adding another muffler, reconfiguring my genset mount (so I can use it finally). Also I'm sticking to the East coast, and not crossing the Rockies anymore.
I wanted to get a direct drive tranny, but I ended replacing the one I had with the same model.
Again, I still drive 55 unless I'm rolling through mountains, then I just her her do what she wants.

Doghouse I'm pretty sure you already have a direct drive tranny.

Allan,..I'm really not sure,..I asked for one and the guys who sold me the unit said that 9th was the direct drive gear and 10th was not. Then again,..they were bumbling fools anyway.