On the new 2019 they will be a little small. The 21" wide flaps will fit better. Truck Hardware is working right now to modify the custom fir bracket to work. There are a few small tweaks that need to take place in order to get the fitment just right. They will be available very soon.
Yes, here is the full truck set with everything you need for the truck,
https://www.sharptruck.com/2019-20-ram-3500-ram-head-logo-gatorback-dually-mud-flaps-set-with-oem-flares
Here are the two part numbers you need for a truck with OEM fender flares,
Rear flaps: https://www.sharptruck.com/truck-hardware-gb2124rv
Rear mounting brackets: https://www.sharptruck.com/truck-hardware-gb768052
here is the bracket for the 19" wide flap, https://www.sharptruck.com/truck-hardware-gb768068
There is an install video on the page that will show you exactly the steps to install on your truck