I've swapped the interior including the rear seatbelts into my 83 from a 91 'Bird. The rear mounts were welded in place so that I could use the shoulder belts. The passenger side fits perfect, but the drivers side almost 1 1/4" too high. The mount is in the correct place. Could the inner fender wells have changed?? Does anyone have a pic of that side of the car, possibly when doing an interior swap? Please help, I'm so close to having this car done!

 

On closer examination, there's absolutely no way to make the belt fit without major modifications to the wheel well.