Idler arms early a vs 67 up cars

I am considering modifing my 65 K-frame to accept the later model idler arm so I can take advantage of the added frame mount and a through bolt at the frame pivot. Do any of you know if the mount end is all that changed? Is the taper at the center link the same? Is the overall casting dimensions the same making the mount the only difference? Have any of you made a similar modification?