Opinions on a Cascadia Glider with 12.7 and ALLISON 6 speed fully automatic?

Modern engines are tuned to run in a fairly narrow power band. Outside of this efficiency drops off quickly. With a ten speed, you might gain 200rpm in a downshift, going from 1500 to 1700rpm. With only six speeds, you need to either program the ECU to give a higher redline, or you will need to lug the engine down to 1100-1200 to keep from over revving on a downshift. Same for shifting up, if you have to wind it out in order to even get reasonable torque in the next gear it's not a good thing.
If you have 550-600hp and 2400ft/lbs on tap then it's not an issue, excep the TBO gets a bit short when the clutch packs and torque converter clutch try to keep up.

 

Here is a thread to a happy customer.
http://www.thetruckersreport.com/tr...ern-star-dump-with-dd-13.291386/#post-4868346

 

Why not the DT12 if your looking to go auto? I'm not a fan of auto's but If I was forced to go auto that would be my pick. 228wb dragging around a 48 doing food service they averaged high 6's across the board, limited at 62. Was just in one the other day that was at 6.6 over 110k miles. Direct drive with 2.64's and the older ones with 2.47's. The 2.64's get better mpg than the 2.47's

 

Where the Allison really shines is when you're running 6x6 units in places you would only see a highway tractor in if that driver ####ed up REALLY bad, except their trucks get stuck well before they make it there when that happens.
On the highway... IMO, the gaps between gears are a bit wide to be ideal.