Ramboxes have been around since 2009, and to the best of my knowledge has only been a problem on the 2019 trucks.
I had them on mine since 2013 and never had a day of problem with them. It's only now that the problems seem to be coming out in quantities, and I believe it has to do with not only a material change (in an effort to save weight and get better fuel economy), but also a vendor change.
I don't know why a solution of going back to what it used to be can't be considered, but I'm sure there is an answer for it much more definitive than what I just said about vendor change.
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Yeah, I'm thinking it's one of three possibilities. [1] the new materials (all plastic, I assume?) are not able to withstand the uneven heating caused by the sun's rays, [2] the material is OK but the design is wrong (i.e. there isn't enough section thickness or structural ribbing in the design to resist warping and maintain straightness), or [3] the moulding process is imparting stresses in the parts that take time, and heat, to manifest themselves and relieve the built-in stress by bowing upward. Could be something else, too, but those are the three possibilities that occur to me.
I hope Ram jumps on this and fixes it
correctly, and pronto. I'm guessing they might possibly do that, because this is a very visible defect, seen by the public every time these warped-lid trucks are out on the street or in bparking lots, thus a notable black mark against the perception of Ram's quality control.