The 2006 allison trannys (GMC & Chevy) have a toggle switch and a "M" or manual mode. In this mode you can toggle up and down through the gears. What ever gear you are in is the initial gear when you go from "D" to "M". I use tow/haul in drive and cruise control for most every towing situation. The exception is for extreme down hills or rough roads where the computer cannot possible know what's happening. For these unusual situations the "M" comes in real handy.
Dave and Victoria
Half Time Full Timers or is that just half full 0f it?-- whatever!
'06 GMC3500 DRW CC 4x4 Duramax/Allison
Bubba Truck
Pulling Cambridge 358
Sharing with a Yorkie (Dude) and a Schipperke (Dharma)
Click here to read a detailed report on our Cambridge