Our Expy is a 2009 with the heavy duty tow package and 3.77 gears. We pull a 29' (without hitch) with little problems. I get pushed around at times by semis on the interstate, but I am making some adjustments on my WD hitch that I think will cure the problem. I have plenty of power, but I have not pulled any mountains. I have pulled from the Chicago area to Omaha and up into Mich with no drama. I have read that with the six speed transmission, the low gearing isnt really needed, but this is what I wanted. We travel light with now water either. Hope this helps.