This is correct, there is no longer a 3.42 ratio in Ram trucks. Payload is nothing more than the GVW rating of the truck minus the actual weight of the truck, simple math There is a sticker on the door jamb of every new truck that shows the payload among other things. Look at any of them on the lots. The Ram websites are not accurate as far as payload ratings. The only way to know for sure is to go weigh the truck at your certified scale of choice. Keep in mind the more options the truck has the lower the payload, because it is heavier. Anything you add reduces the payload, people, pets, camping gear, fire wood, tools, etc.
My ‘19 3500 Longhorn SRW has a payload of 3797, the Ram website where you can put in the VIN to get the payload says mine is 4110. The tow rating for my truck is about 24,000 pounds.