Guys, I have a 2001 Dodge Cummins. Drove into Sedalia , Missoui today and Chevy Dealer had a Red 2001 Regular Cab Durmax/Allison 5 speed automatic, & I drove it about 10 miles. Smooth & Quiet with hardly any vibration. Allison trans is very low geared when taking off. Just punching it from stand still and not torqueing engine up she will burn tires for about one truck length. Faster than my stock Cummins & transmission felt better, like the way it de-celerated and gave some transmission braking also. As soon as I hit the road and got up speed I told the salesman how great it steered, I was impressed with steering and no wondering, it steered tight and percise, unlike my Dodge. Engine likes to rev up easily. Jumping on throttle at 60 mph it down shifts, but at 70 mph jumping on it it stayed locked in highest gear. Wish I could have driven it more, it was fun. Did not drive it faster than 85 mph, but it really wants to haul butt! It was a great experience!