Concerning dry weight: difference between BP vs 5er

my 2004 Ram 1500 with V6 and manual transmission could only tow 3,300 pounds DRY TOTAL.... I was able to get a Amerilite 21 foot bumper pull... and it was to small for 2 adults. and was very HARD on the truck... and LOTS of shifting from 4th to 2nd...on almost any hill.

think of going 50 miles per hour up small hills in 2nd gear at 4,500 rpm.
and that truck had 30,000 miles on it.