Depending on what missions you have completed up until this call will determine the amount of Stereo Jackers that you must kill. This is why the mission is listed as Kill 40 OR 60 Stereo Jackers..

The trigger point for this mission seems to be near 135581,83890

(12/27/2018) Avatar "Franki Fenix Amador" Last actualization:  When i was doing mission "Rocktropia Police Call: 11-25", i was walking looking for Soulshakers; in Position (135729,  83495, 199) was the trigger for this mission.  Both missions can be at same time....