Abstract: An anchor for a seat belt for a seat for a mobile vehicle such as medium or heavy-duty truck, the vehicle with the seat belt anchor installed, and the process of back fitting an existing vehicle with a seat with a seat belt. The seat belt anchor may be installed in a vehicle cab either during manufacture of the vehicle or in the after market. The anchor provides the surface area required for providing the strength required by Federal Law and fits around existing components of the cab. The anchor has at minimum three sides to roughly form a `U` shape to fit around a vertical gusset and mounting surfaces or flaps or engagement to the cab structure. The critical geometry is that the anchor will fit around a vertical gusset or cab support. In the primary embodiment, the anchor has 5 sides. The three center sides generally form a `U` shape when viewed at a downward angle from the rear of the cab. The `U` will fit around a rectangular cross-sectioned vertical gusset or cab support.