A catheter system, comprising: a catheter, wherein the catheter comprises a catheter body having a lumen; a core received within the lumen of the catheter body; a rotator coupled to a proximal end of the core; a first set of electrical contacts disposed on the rotator; and orienting splines extending from opposite sides of the rotator; and a drive unit, wherein the drive unit comprises a rotatable shaft connector (65, 265) comprising a shaft with orienting slots (67, 267) at opposite sides, the orienting slots (67, 267) configured to mate with the splines, the shaft connector further comprising a plurality of beveled surfaces (70, 270) with two of the beveled surfaces sloping into each of the orienting slots (67, 267) from opposite sides of the orienting slot, the rotator and core adapted to rotate with the shaft connector (65, 265) when the splines are mated with the orienting slots (67, 267), wherein the orienting splines, orienting slots (67, 267), and beveled surfaces (70, 270) are configured so that the first set of electrical contacts do not begin to engage the shaft connector (65, 265) until a full width of each orienting spline is in the respective orienting slot (67, 267). a catheter, wherein the catheter comprises a catheter body having a lumen; a core received within the lumen of the catheter body; a rotator coupled to a proximal end of the core; a first set of electrical contacts disposed on the rotator; and orienting splines extending from opposite sides of the rotator; and a catheter body having a lumen; a core received within the lumen of the catheter body; a rotator coupled to a proximal end of the core; a first set of electrical contacts disposed on the rotator; and orienting splines extending from opposite sides of the rotator; and a drive unit, wherein the drive unit comprises a rotatable shaft connector (65, 265) comprising a shaft with orienting slots (67, 267) at opposite sides, the orienting slots (67, 267) configured to mate with the splines, the shaft connector further comprising a plurality of beveled surfaces (70, 270) with two of the beveled surfaces sloping into each of the orienting slots (67, 267) from opposite sides of the orienting slot, the rotator and core adapted to rotate with the shaft connector (65, 265) when the splines are mated with the orienting slots (67, 267), wherein the orienting splines, orienting slots (67, 267), and beveled surfaces (70, 270) are configured so that the first set of electrical contacts do not begin to engage the shaft connector (65, 265) until a full width of each orienting spline is in the respective orienting slot (67, 267). a rotatable shaft connector (65, 265) comprising a shaft with orienting slots (67, 267) at opposite sides, the orienting slots (67, 267) configured to mate with the splines, the shaft connector further comprising a plurality of beveled surfaces (70, 270) with two of the beveled surfaces sloping into each of the orienting slots (67, 267) from opposite sides of the orienting slot, the rotator and core adapted to rotate with the shaft connector (65, 265) when the splines are mated with the orienting slots (67, 267), wherein the orienting splines, orienting slots (67, 267), and beveled surfaces (70, 270) are configured so that the first set of electrical contacts do not begin to engage the shaft connector (65, 265) until a full width of each orienting spline is in the respective orienting slot (67, 267).