An apparatus for adjustably coupling a threaded linkage rod to an arm of a fuel valve, air valve, air damper, damper blade assembly, or actuator that can include a sleeve, a collar, and a lock restraining axial movement of the collar with respect to the sleeve. The sleeve may include an inside threaded wall defining a sleeve bore axially receiving the linkage rod. The collar may include (i) a collar body having a collar bore axially receiving the sleeve and (ii) an about radial extension for engagement with the arm of the fuel valve, air damper, or actuator. Rotation of the sleeve causes axial movement of the sleeve, and thus the collar locked thereto, along the linkage rod. Fine position adjustments can be made to the position of the radial extension, and thus the arm of the fuel valve, air damper, or actuator engaged thereto, with respect to the linkage rod.