[Walt Fricke]

Did the Euros not come with seat belt retractors? All the US SCs had them. So the connection to the B pillar was a D ring (held by a shouldered bolt like what guys have shown), through which the belt ran. The retractor itself doesn't need a shouldered bolt.

Having shouldered belts can be pretty important. The piece of hardware you attach with a bolt needs to swivel, so that the angles of pull are always perpendicular to whatever - D ring or end piece) is taking the force. That way the nylon belt is loaded evenly across its whole surface, should a sudden deceleration occur. If the piece is at an angle to the pull, all the force will be exerted on an edge of the nylon strap initially, and a force which the whole belt could hold might be enough to rip at the edge, which will proceed diagonally across the belting. This is what happened to Dale Earnhardt (force unevenly distributed, though not due to not having a shouldered bolt).