Download the specific shim kit for your Truck:

GM  150 2019 & +

    • Master 50 Long bed
    • Master 60 Short bed
    • Master 60 Long bed
    • Master 75 Short bed
    • Master 75 Long bed

Lock-Down Procedure



Install the shim kit as on the drawing that you can download above with the right truck model


a) Place socket into access hole inside Master.b) Slide socket over bolt and push socket firmly to clear lock-ring on bolt.c) While pushing socket over lock-ring gently rotate counter-clockwise to lower arms.


(These are usually preset for initial vehicle type at factory)


a) Center Master from side to side


a) To raise lock-down arms place socket into access hole from inside Master.

b) Place socket over bolt pushing socket in firmly to clear and free lock-ring activation bolt.

c) Pushing socket over lock-ring gently rotate clockwise C to secure lock-down arm in clamping position. Use Caution not to over tighten or rail may become damaged. From the fully down position full clamping engagement is approximately 6 – 7 complete turns.


a) Ground Wire

b) Power Wire (for Interior Lights & 12V Auxiliary Power Plug)

c) Third Brake Light

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