Truck bed height

I currently have a 04 GMC 2500 2wheel drive that tows a Newmar 5er. I want to replace my tow vehicle with later year and less miles. Upon looking and measuring a 2014 Dodge, I found the bed too high. I do not want to do a lot or raising the front of the trailer. What years did the bed height start raising on the Dodge and the GM trucks? This will let me know what years I will purchase. Thanks to all who reply.