I assume you have an auto tranny? My '97 2500 Dodge CTD had the 47RE transmission. Letting off the throttle would unlock the TC and the truck would freewheel down the mountains. I installed a PakBrake exhaust brake after the first tow that heated my brakes up. Most of the problem was following a flatlander driving a semi with a load of hay coming down Berthoud Pass at "OMG Terrified!" speeds of 10 MPH and wouldn't pull over to let traffic go by. In retrospect, I should have been the one to pull over and let him get 30 minutes ahead!
However, you said EB is not an option, so, for non-Rockies kind of slopes, the above recommendations are the best I can say "ditto" to ... except the unlocked TC...
someone suggested a little bit of throttle keeps everything locked up and you can then get some engine braking but that was after I installed the EB.
My 07 Ram 2500 CTD has the 6 speed manual, so I get more control over gear selection and have not yet felt the need for an EB ... yet.