A machine for coupling a plunger rod to a syringe assembly may include a carriage including a cradle having a seat portion sized to receive a syringe assembly and an aperture portion disposed above the seat portion and sized to receive a plunger rod. An actuating device may be operatively coupled to the carriage and adapted to move the cradle from a first position to a second position to couple the plunger rod to the syringe assembly. The carriage may be selected from separate and interchangeable first and second carriages, wherein the first carriage includes a cradle adapted to receive a syringe assembly of a first size and the second carriage including a cradle sized to receive a syringe assembly of a second size that is different from the first size.