Truth Split Arm / Dyad Operator - Casement window

I have found a couple of similar ones on your site but the measurements do not match. From the middle of the gear to the connector of the outer metal piece is 5". The outer metal piece is 4" from the rivet to the outer hole and has 20810 stamped on it. On the back side of the base unit in raised numbers I see RH 45136. US PAT 4505601. I believe our windows are Marvin.

I need to replace it as the gears have worn out and it will no longer close the casement window.