HI 75! oh boy, that kingpin and plate were easy but you should see the rest of the mess! this particular box has a hydraulic piston mounted right in front of the box. the kinpin and plate were installed first, then this massive pedastal was welded to the plate and the box beam frame, then the 10ga. bed was added on the inside of the box and welded all around. i'm scarfing and peeling the remains of the fifth wheel plate where everything is welded and sandwiched together. i"ll have to weld a new 1/2" base plate for the pedastal. then install the kingpin and plate and plug weld the plate to the bottom of the new 1/2" pedastal base. you never what you are geting into.