Well no luck at the aircraft salvage yard on a wiper arm. However, did find a Piper aircraft arm with the same drive motor attachment piece, but the arm itself is a U shaped channel, not round like the Boeing unit. Found another arm with the correct wiper connection, but it to has a U shaped channel for an arm. These ends are brazed on which I will "de-braze". Just need some round section DOM tubing to braze/rivet on the ends. Will post pictures when done. Hope it turns out as well as Pedro's units above. Question... anyone have any idea of the diameter of the arm, looks to be 3/8 or 7/16"?