It didn't come with instructions?
EDIT: Just got a call back from them. Two go behind the rear axle and the third goes on the passenger side on the bed closest to the cab. They said some trucks have a gusset there that may inhibit the normal block from fitting in there. Not sure why they don't put that in the instructions...
There are instructions, but there are 3 skinny blocks which isn't symmetrical. Why are there 3 and not 4 or 2? Why aren't they all the same size? I called PA and I keep getting their voicemail.
This is what the instructions say:
18. Remove the bed mounting bolts from the passenger
side of the bed only. Using a hydraulic jack and a wooden
block, slowly lift the bed just high enough to place the
spacer blocks on the bed mounting pads. The small block
goes on the mounting pad just behind the rear axle.
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