After 244,000 + miles on my 91 Chevy S10 P/U I finally burnt it up (Water pump leak). I purchased a 2001 Dodge Ram 1500 with V8 engine and auto. transmission. The tranny is equipped with overdrive. There was no owners manual in the truck when purchased. My question is do I use O/D when towing a trailer? I currently pull a 5 X 8 open trailer loaded with equipment and 2 extra storage boxes loaded with spare parts, hand tools, fluids, etc. I have not owned a truck with O/D before so this is new to me. Any help will be appreciated.