Vibration or shutter when backing up?

The shudder in reverse only is unfortunately a known part of the 42RLE and many other Chrysler transmissions. Commonly a transmission service with a new filter and fluid helps. Just be sure to use the correct fluid and not one of the universal ones that are out there. Should be around 4 quarts of ATF+4 for a simple filter change, however I would get twice that and then change it twice to get more of the old fluid out. The use of the wrong fluids in that unit will cause more shudder. The basics of the change are to get under the vehicle, set up a drain pan and remove the bolts that hold the pan in place. Leave a couple in by a few threads to catch the pan. Tap the pan to break it free. Then remove one of the bolts holding it up and tilt it so the fluid can run out. Now remove the others and lower the pan. Drain the rest, wipe out the pan and reinstall it temporarily. Add 3 quarts to the transmission and start the engine, shift it through each gear. Shut the engine off and repeat the pan removal. This time wipe out the pan and change the transmission filter as well. Refill and check the level and drive it.

https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid

Yes, typical of a lot of the newer Chrysler transmissions. It's because of how the solenoids select the various gear ranges in the transmission. When you want to worry is when it starts to shudder while going down the road at about 40 MPH or so. That is a sign of the converter failing as it loses the friction material on the lock up surfaces.