A receiver assembly for capturing a connecting member in a receiver of the receiver assembly via a first threaded closure and second threaded closure that are interchangeable for different locking configurations in the receiver assembly, the receiver assembly comprising:
- the receiver having a central axis, a base portion, and an upper portion defining a first channel configured to receive the connecting member, the first channel extending between a front face and a back face opposite the front face of the receiver and communicating with a top surface defining a top of the receiver, the receiver having interior surfaces and exterior side surfaces opposite the interior surfaces, the interior surfaces having a helically wound receiver thread formed in at least a portion therein, the exterior side surfaces extending horizontally and radially proximate the top surface of the receiver, each front face and back face having a planar surface extending parallel relative to each other and the central axis with outer ends of each of the exterior side surfaces opening onto the planar surface on each front face and back face of the receiver, and the receiver including a lower pressure insert at least partially positionable within the first channel having upright arms forming a second channel therebetween and defining a rod seat surrounding a central opening for a tool to pass through, the upright arms extending above a top surface of the connecting member positioned in the second channel against the rod seat;
- the first threaded closure configured to be positioned within the first channel to capture the connecting member in the receiver, the first threaded closure comprising a first cylindrical body with a first outer diameter having a first longitudinal axis, a first planar top surface having a first central internal drive structure with a first tool abutment surface comprising a first centralized through-bore around the first longitudinal axis, a lower surface defined in part by an inwardly positioned downward protrusion having a second outer diameter less than the first outer diameter, an external side surface on the first cylindrical body having a continuous helically wound thread configured to rotatably mate with the helically wound receiver thread, and a first bottom surface on the inwardly positioned downward protrusion communicating, the first centralized through-bore extending from the first planar top surface to the first bottom surface, the first bottom surface configured to compressively engage the connecting member positioned against the rod seat of the lower pressure insert so as to lock the receiver assembly;
- the second threaded closure interchangeable with the first threaded closure configured to be positioned within the first channel for capturing the connecting member in the receiver, the second threaded closure comprising a second cylindrical body with a third outer diameter equal to the first outer diameter of the first threaded closure and having a second longitudinal axis, a second planar top surface having a second central internal drive structure with a second tool abutment surface comprising a second centralized through-bore around the second longitudinal axis, a second bottom surface with an annular outer edge adjacent a second external side surface on the second cylindrical body, the second centralized through-bore extending from the second planar top surface to the second bottom surface, the second bottom surface configured to compressively engage the upright arms of the lower pressure insert and be spaced apart from the top surface of the connecting member positioned in the second channel of the lower pressure insert, and the external side surface on the second cylindrical body having a continuous helically wound thread configured to rotatably mate with the helically wound receiver thread so as to lock the receiver assembly,
- wherein when the receiver assembly is in one of the different locking configurations via the first or second threaded closure in the receiver, the first or second threaded closure does not extend over any part of the top surface defining the top of the receiver.