Listed here is a pack of 1/12 scale FULL BALL Throttle Linkage with Bolts to mount them. 

This design was primarily used in the 60s. All parts are machined aluminum except the stainless steal tubing that is also supplied.

The ball diameter of rod end is .055" (1.39mm) with a .021" (.53mm) bolt bore. Rod End is machined flat on one side only to make a full ball design from years past. The sleeve of rod end is drilled to accept the .020" (.50mm) steal rods. A
.035" (.89mm) hex jam nut is also supplied that fits over the tubing and
butts up against the rod end.

Package contains 4 rod ends, 4 jam nuts and 2 pieces of tubing 1.5" (37mm) long. Also supplied are 4 machined aluminum .031" (.78mm) hex bolts (no threads) to mount them.

There is no specific application for this part so you will have to come up with your own use.