Built by the Erie Railroad at their Dunmore, PA shops in 1945-46, the N3A class was given CR 19653-78 on the roster.
46101 is an ex-EL caboose wearing an "R" designation, meaning it's in restricted service (as also evidenced by its MOW gray paint job. These specially designated cars were to be kept to special service due to their ages or conditions. In this case, probably the friction bearing trucks.
One of the rare ex-EL N-3A cabooses holds down an assignment on the Greenwood Branch alongside an ex-Reading MP15DC.