That slider is already broke, that is for sure.
Might be why the customer never picked it up as well. I would reject it, as well ;)
The earlier versions were molded in color, but the later ones were painted. I've bought two passenger side ones before and noticed the difference myself a long time ago now.
The date on the box states 04/02/96, so definitely a newer part run.
I've fixed these before by using a small drill and four small screws with large for their size heads, like you would find in old electronics that held parts to a mother board.
Truck: 1981 F-150 Explorer / Engine: 300-6 California MCU Feedback System / Trans: T-18 - 4 speed / 2.75 Ford Rear Axle Open Diff.