10 inches the slider assembly 10 fig9 may also include spacer members 80 positioned between the distal end 51 of the support bracket 38 and the guide plate 54 thereby accommodating for vehicles having variously spaced frame rails 12 with commonly dimensioned support brackets 38 engagement assemblies 58 and the like as best illustrated in fig1 and 11 a stroke depth adjustment assembly 82 includes a mounting block 90 coupled to an end of the pneumatic cylinder 70 by a bolt 84 at a first end 86 and threadably receives an adjustment bolt 88 within a second end 90 in operation a head 91 of the adjustment bolt 88 abuts an inboard edge 92 of support bracket 38 as the engagement members 60 are moved from retracted position to the extended position thereby limiting the stroke length of the pneumatic cylinder a locking nut 94 allows the adjustment bolt 88 to be locked in a preselected position with regards to the mounting block 90 thereby allowing the effective length of the engagement assembly 58 to be adjusted for vehicles with variously spaced frame rails 12 as best illustrated in fig7 the slider assembly 10 may also include a sensor assembly 100 adapted to sense proper positioning and locating of the engagement pins 64 within the apertures 72 of the angle bracket 20 and apertures 74 of the guide plates 54 the sensor assembly 100 sends a signal to a logic controller 102 which alerts the driver to proper alignment and or misalignment situation.