Retainer for equalizer bar pin and systems and assemblies thereof

A retainer plate configured to retain a center pin for an equalizer bar comprises a first face and a second face opposite the first face; a first support arm having a first reduced contact portion; a second support arm having a second reduced contact portion; and a neck portion between the first support arm and the second support arm. The retainer plate can be symmetrical about a center vertical axis in an end view thereof, and the first support arm, the second support arm, and the neck portion can define a central concave recess configured to receive the center pin via an opening into the central concave recess defined between the first support arm and the second support arm. The first support arm can have a first set of openings through a thickness of the retainer plate and configured to receive respective fasteners therethrough, and the second support arm can have a second set of openings through the thickness of the retainer plate and configured to receive respective fasteners therethrough.