Yes, you can replace the rear ones with no resistors because they are already wired for LEDs.
for those searching, I can say this is not true. I put some LED's in the rear of my 2017 after reading through this thread and they most certainly hyper flash. Not keen on hacking up the wiring of a truck with 300 miles on it, so I guess I have to go back to the standard bulbs. It is too bad cause the LED's from XenonDepot look awesome.