72 Dart bench seat dimensions

Can someone help, I recovered a bench seat but didn't have much to start with so I don't know where the seat belt plastic tunnels go. I need to know where these tunnels that the seat belts go through to the floor belong. If someone could help with dimensions from the center line of the tunnels to the back edge of the lower seat and the distance between the center lines of both the tunnels across the seat. Any help would be appreciated. Thanks FABO, Mitch