15 spd trans

15 speed is basically a 10 with 5 more low gears. I believe that you want a 13 speed.

 

15 is more suitable for construction sites and off road with heavy loads. It splits the bottom 5 speed.
I have a 15, the most weight I haul is legal 80 gross. I might use the 3 gear in low low to start on a hill and shift in to 6 gear and go from there. Lighter loads or on flat. I almost never use the low range.

 

Engine makes a rated torque you wont get "More"

What you might have a chance to do is increase the reduction so that the engine appears to give you more torque.

I agree with other poster 13 speed will do it. 15 seems like a 10 speed that makes you work unnecessarily.

 

The 15 is such a specialized transmission. You can split the low range down, but it isn't progressive. In normal on road it is the same as a 10, except heavier for something additional that is useless. Unless you need the granny gears, stick with 10 or get either a 13 or 18.

 

15 is just a glorified 10. Its called a 15 but starting in the bottom and shifting progressively you'll only use 12 gears due to overlapping ratios. (5 in deep reduction, 2 in low and 5 in high). 15 speed has no splits, just deep reduction which is just 5 slightly lower gears below low range. 13 or 18 would be a better choice IMO.

 

IMO 18 is the only way to go. ESP if you'll be heavy or off road at all. 13 is ok for legal weights and some offroad.
I wouldn't take a 15 if it was free. Final ratio on a 15OD is higher than the .73 final on a RTLO trans (.86or .87 I want to say) and if you end up with a 15 direct you're really ####ed for highway running. Maybe ok for around town dump trucking.

 

Plus the 15 over has a funky shift pattern with top gear being up against the dash.

 

Not all 15's have that "funky" shift pattern. I've driven High gear against the dash and normal 15's. Depends on how it was ordered.
Now as far as a 15 being the same as a 10..........nope not even close! Most 10's these days really only have 7 or 8 usable gears on road. You use all 10 with the 15. I liked 15's almost as much as my favorite 13's! Hated the 10 speed meritor in my last truck.
Plus a 15 will go like hell in reverse!
One drawback to 15's is they are pricey to fix compared to other transmissions.
JD

 

Correct . The newer 16915 has a normal shift pattern.

The 15 has smaller % steps between gears then the 10 speed also.

Nothin wrong with a 15 , they shift beautifully and are super strong.

I'd take one any day over a 10 speed.

But ultimately an 18 rtlo is the best trans for almost any job.