I’m pulling a 2 horse slant w/ huge dressing area w/ 1 horse(about 1000 lbs) and camping supplies w/ 35 gallons of H20, The Truck is an 2006 Big Horn edition w/ extended bed. My question is when I have the truck in tow/haul and I’m climbing a mtn and I hear the truck engine sound different and notice it losing speed should I put it in D2 or use more gas? I know that when I’m going down hill I should put it in D2 to save on the breaks but am not sure what to do when climbing, my friends(women)tell me that when you have the tow/haul on you shouldn’t have to use the D2. I would greatly appreciate any advise. Thank you
Is your engine type listed in your post. What does it mean when you say “have the tow haul on”?
Any indication what RPMs your engine is running at when you want to downshift?
What RPM does it go to when you do downshift?
Downshifting is immensley preferable to lugging the engine.
engine type, gas V8(sorry I don’t know more than that about it)
RPMs, I didn’t take note of them(my girlfriends asked the same question, I’ll have to take notice of them next time I drive)
thank you for your reply
Your answer should lie in the manual. Typically d3 is a recommended option as it should downshift when needed, cruise control should be off.
Thank you Waterboy, you’re right. Cruise control was off and had it in Tow/Haul I’ll read up on it tonight. 
When you’re going up a hill, just let the transmission do the thinking-- leave it in high gear and push the gas if you want to go faster. The only time you’d really want to downshift while going uphill is if you’re on a grade where the transmission keeps “hunting” between two gears.
You definitely do need to downshift the transmission on the way down though.