A sheet stacking system for transporting sheets and depositing them in a stack includes a layboy, a transport conveyor downstream of the layboy, and a main conveyor downstream of the transport conveyor, the main conveyor having a frame and being supported by a conveyor support, a discharge end of the main conveyor being movable between a lowered position and a raised position relative to the conveyor support. The main conveyor intake end is configured to move from a first position when the main conveyor discharge end is in the lowered position to a second position when the main conveyor discharge end is in the raised position, and also a variable length conveyor between the transport conveyor and the main conveyor, the variable length conveyor having a discharge end connected to and movable with the main conveyor intake end and movable relative to the transport conveyor discharge end.