Differential Cross-Pin Link
Link for the 'NEMA17 Rocker-Bogie Mars Rover Chassis' kit (print ×2). It has 40 mm between hole centres and joins the 625 differential bar end to the rocker ear. End A is a 12 mm OD × 6 mm eye with a vertical 3.4 mm hole. End B is a 10 × 12 × 12 mm boss with a 3.4 mm cross-hole along Y, 6 mm up. The two hole axes are perpendicular, so the link works as a cardan-style joint. Each end takes an M3x25 bolt with a nyloc nut and washers.
robotics kit rocker-bogie linkage