Originally Posted by Mr_D
Wish we had a 10 speed in front (since it's a DP) of our ISX rather than the Allison 4000MH.
My 10-speed trans is an Eaton Ultrashift, which is basically a computer controlled clutch and shifting manual trans. I do not have a clutch pedal in the cab, just a keypad with R-N-D. The computer does all the clutch and shifting work, you just press the throttle as driver. There is a std dry clutch and the trans has traditional manual gears, just that the functions are controlled by the computer. The 10 speeds are good for being able to keep engine in the best rpm for the conditions. Better than the 5 or 6 in the Allison automatics. Although I have to put up with more shifts and a bit less smooth compared to the Allisons. For example, mine has shifted four times by them time I am at 25 mph.
Most truck conversion based on class 8 big rig chassis will have a manual trans or one of the computer controlled automatics. 12-speed auto-shifting is now common. Several trans mfr's make 12 speed versions.
Back to OP, it really comes down to preference and what fits your needs. A Class A, Class C, Super-C, or Truck Conversion can all work; depends on what you want to do with it, how much stuff you are hauling or towing, amount of space, floorplan, and features. All it takes is money