4. Rex Burkhead
Yes, Burkhead looks like a bad combination of old (32), little used and constantly banged up over the course of his career (10 seasons). But the devil's advocate view says he doesn't have much mileage on his legs (488 career carries) for the age he is, and he has been a capable passing down back right along (37 receptions last year for the Texans).
As a short-term depth option while Montgomery is out, Burkhead reeks of the kind of consummate professional role-player type back the Lions should be looking for. Having him in for a workout isn't out of the question.
3. Ronald Jones
It was a slow climb for Jones over his first three NFL seasons with the Buccaneers (978 yards and seven touchdowns in 2020), and it's been a pretty fast fall since. He barely played for the Chiefs last season, then the Cowboys took a chance on him this offseason. Then they cut him after he returned from suspension in September.
Jones is still just 26, and the potential he flashed for the 2020 Super Bowl champs is presumably still in there somewhere. Someone might still try to find out, and as a sheer flier to fill a short-term void the Lions could give him some sort of a shot soon.