A dual sack rack frame (10) allows mail sacks (12) and (14) of different sizes or, alternatively, tray receptacles (100) and (110) to be used as output for the small parcels and bundles sorting system used by the United States Post Office. The mail sacks (12) and (14) are connected to rear, pivotable, spring biased retention hooks 46 and front, stationary hooks (50) or (52), respectively. The tray receptacles (100) and (110) are positioned on tray supports (36) which are pivoted downward when mail sack collection is no longer desired. The dual sack rack frame (10) is easily exchangeable with other collection receptacles by simply pivoting the chute support brackets (32) to a non-supportive position and detaching the plunger pin (22) which connects it to the stabilizing frame.