Tow Haul mode on my truck is put it in 6th and floor it![sm=gears.gif]

 

So help me here. What exactlty does the tow haul mode do. I have been towing my 35 ft 5er not in tow haul and granted not up any really big grades but it seems to work just fine. Coming down the other side I have used tow haul and the exhaust brake but it seems to shift in and out really hard. Is this normal?

Should I be using tow haul on the flats? I usually run about 60 mph and am turning 1700 rpm in 6th.