I started out years ago towing our 7,000 lb trailer with my old chevy 2500 with the 350. I tow mostly in the Sierra and Rocky Mts. I hated the way I had to slow down to 45 mph going up the grades. So ...
Thanks again for all of the replies. When I tow at 3000 and higher RPM we get in the 4-5 mpg range. At 4000 rpm the truck is very loud. I am not normally in a huge hurry when I an towing and never go more than 68mph but when you are on a two lane highway in the Mts and you have to slow down below too much, then you wind up in the truck lanes and stuck behind them going 35-40 mph and losing all momentum.