The rear bed mount will need to be shimmed up if it is lower than the front corners. The front bed corner adjusters use two of the screws that hold the upper rod bearings to secure them in place. You will need to obtain two 3mm screws (I used the socket head type) that are 12mm long. Thread these into the front bed adjuster arms until the ends of the screws are flush with the top of the arms. Remember to loosen - but not remove - the two inside bed mount screws so the adjuster has room to push upward. Make small adjustments using the 3mm screws to raise the front corners - no more than a 1/16 of a clockwise turn at a time.