The 2010 6.4L diesel does not have a bad reputation. From all reports has been a good motor. The early job 1, 2008 6.4L diesels had a few ECM, radiator and injector issues. They were fixed. The later 2008s - 2010s have had a very good reputation. The 6.0L diesels (especially the earlier years) are the ones known for issues. the 6.0L was from 1999-2007).
The latest generation (2011+), 6.2L diesel has been surprisingly good for reliability (new engine built by Ford).
For the OP, a 2 WD diesel pickup is a hard sell. Not many people want them. At the minimum, it should have limited slip rear differential for 2 WD.