This work guide deals with the fitting of retractable belts to the front and rear of a 6 seater sedan (bench seat front), I had to do this because of a rapidly growing family.

The first thing you'll need is some Klippan belt kits, you can get these from many auto retailers or rare spares. The kits I used are:
K2258R - Front or rear lap non-retractable belt kit (red)
K2255R - Front lap sash retractable belt kit (red, vertical mount)
K2256R - Rear lap sash retractable belt kit (red, horizontal mount)
The last letter in the serial is the colour designation, so these are naturally red.
So being a bench seat front the car gets 6 kits to keep it a 6 seater. The front gets K2255R on the pillars and K2258R in the center and the rear gets the 3 sets of K2256R on the parcel shelf.