How are these specs
 

This would be for a truck running 48 states but since I live in Sacramento, there will be a fair amount of mountain climbing.

Cat C15 2007 475 @ 2100 and 1650@1200
Fuller RTLO16913A
3.36 ratio

Bridgestone R287 295/75R 22.5 14ply Steers
Bridgestone M720FE 295/75R 22.5 14ply drives

Anyone have any opinions on the Espar/NITE engine off system? From what I can tell, it takes 8hrs to charge for 10hrs of heating/cooling, which will be useless during 34hr restarts during hot/cold weather without idling. I'm assuming it's only for heat/ac and not for appliances such as a fridge and microwave. I think I would rather have an APU...

You plan on buying a truck is that the spec's of your T600? 3.36 isn't much of a pulling ratio, especially when it comes to mountains. If your gonna be running mountains alot I'd go with a 3.58 rear ratio it'll have the pulling power for hills and get good fuel milage on the flat land. I think thats right correct me if I'm wrong on that! I'd rather run a Detroit or Mercedes over a CAT or Cummins (Born and raised Shaker fan) and a 13 spd is good!

It's almost perfect, except I'd want 1850lb torque.
Acert will do good at those specs.

Thanks solo, do you know what the Difference between a 13A and 13B Transmission is?

I think it has to do with the gearset, if the actual gear ratios are different I do not know.

Any 16913 should be fine. If you're going with 1850 torque, you'll want an 18913.