I've probably read every magazine and website review on those trucks out there. A lot of conflicting and inconsistent info, much of it is wrong based on what I have observed at the dealer. (Don't ask the salesman, they are worse!) I think the writer got confused as to what is upgraded from previous years vs what is upgraded between a 2500/3500 for 2020.
Minimal difference between a SRW 2500 or 3500, (springs and ratings) and as mentioned the dually gets a larger rear gear. Watch some of the videos from the truck announcement last winter or at the media drive event last June where they had engineers out talking about the trucks.