lightly used, Tamiya 53325 TA03 Rc Ta03 Aluminum Knuckle Arm (1Pr) - David Jun 58200.  Tamiya part #53325 or OP-325.

The Tamiya 53325 Ta03 Aluminum Knuckle Arm is a vintage option hop-up part designed for the 1/10 scale Tamiya TA03 chassis series (including TA03F, TA03R, and TA03F Pro). Official Tamiya aluminum rear uprights are currently discontinued by Tamiya USA, though aftermarket alloy alternatives can still be found through specialist hobby retailers.
Performance Benefits