Allison vs 8LL in Dump Truck

[The Burren]

I’m tossing around thee idea of adding a tri-axle and I’m stuck on the trans.

I live in Eastern SC which is called Low Country because its flat.  Sandy and flat.  This truck will probably be doing dirt and stone but it may end up (god forbid) as an asphalt truck.  

What are the pros and cons of the 8LL/ Allison?

I test drove the Allison and it was amazing off the line.  Will this change when loaded?  How about fuel mileage running highway speeds (70mph)?  The Allison has 425HP 4.30 rear and the 8LL is 435HP 4.10 rears.  My 05 Granite is 370hp with 4.64 rears and seeing 70+mph means you’re watching the fuel gauge drop in real time.

I’d like to avoid wasting money 

 Thanks 

[Lmackattack]

I have driven a Pete with 425 6nz cat with 8LL and currently Im driving a 350 mack CH with 8LL...   the mack does 65 at 1900 rpm  but it sucks the fuel down pretty good and the gear shift is pretty quick with its slower rears. but its just gutless with that electronic E7. The pete had faster rears wider shifts but did not suck the fuel down nearly as bad. the pete was a great truck to run and was one of the best speced dump trucks I have wheeled. I could do 65mph at around 1700 and it had the power to pull it. the mack takes a mile just to get up to top speed where the pete was doing it in 1/2 mile... comptetly diffrent from each other

The 8LL is good for off road use but the rear end ratio and HP of the engine will make it either good truck or one you will hate to drive... I have to say the pete was set up right the mack is not.

[The Burren]

Thanks for the info.  What rears were in that ch?  I’m going to have to assume that a current 435HP motor with 4.10 will be able to do what I need without working too hard.  Nonetheless I am concerned a bit about fuel consumption on the highway.   What were the rears in the Pete?

[mackcat12]

I have a 2020 Mack Granite Quad axle dump truck with the MP8 455hp and 4500 RDS Allison trans and 4.19 rear axle ratio And this thing is a beast it’s just as fast loaded as it is empty, off road it’s awesome, it does like the fuel I’m averaging 5.7 mpg it seems to get better when I run on interstate. I think you would love the Allison, my 2018 Mack had the MDrive trans and it was ok on the highway but sucked off road.