Originally Posted by Army

I'm interested to hear about these "middle" bolts it doesn't sound like my car has them.

For the driver's seat anyway there are 4 bolts that bolt down through the seat rails into the floor pan.

For the front passenger seat it has these same 4 bolts but also one that bolts in a perpendicular direction into the sill.

My car was built late 1980 - registered 1981... so perhaps an 83 has more bits?

Any chance of a picture?

Alternatively can you see where the bolt is / should be on any of the pictures in this thread?

W123 wonky driver's seat