Just my $0.02, I tow a 3500lb trailer with 3 dirt bikes (750lbs) and tons of heavy gear packed in with my 2014 Ram 1500 with 3:21 and 8 speed and it is AMAZING.  That 8 speed is the best thing since sliced bread.  The truck is always in a perfect gear and rarely screams unless going up a very steep grade and I am on the gas hard to keep speed.  I regularly out accelerate cars and other vehicles from stop light without trying.  I also have an intake and exhaust though, which made a big difference.  That HEMI is so strong.