One of the hallmarks of a dexterous robotic hand is the ability to perform in-hand manipulation (i.e., without re-grasping). In the field of robotic hand design, however, there are competing interests between dexterity, simplicity, and reconfigurability. It can be difficult to achieve all of these objectives simultaneously. This paper presents the design of a simple underactuated grasper which uses a gimbal and parallelogram mechanism to achieve in-hand manipulation while maintaining grasp. The new grasper also integrates elements which make it reconfigurable or metamorphic, and is readily adapted for different types of robotic fingers. The design is validated with a physical prototype, and its performance related to in-hand manipulation is evaluated using multibody simulations, showing improved range of reorientation of grasped objects compared to a more standard fixed-palm underactuated finger design.