My 2018 F250SD 6.2 with the 6R100 trans has a intermittent shudder in reverse, when backup up my 12K fifth wheel up driveway, that has about a 4 degree incline.. Many other owners of same combo on another forum have same issue with 2017-2018. Dealers have not been able to solve.. Putting in 4LO resolves issue, others had suspected parking brake sticking, hill descent control, but no real fix.
Any help appreciated