I towed from Denver to Branson and back for the rally and my duramax only downshifted twice (on big hills near Branson). The Duramax Allison combination just chugs up the hllls like they aren't there. AND I am 500lbs aver my GVWR.
My step son has a Dodge Ram Gasser and it downshifts all time even without the trailer and has been through one transmission already.
DIESEL DIESEL DIESEL
2007 Chevy 2500HD Classic LBZ Duramax/Allison (Stock)
2005 Bigfoot 1500C8.2 AWESOME