hi i used the rear inertia type belts out of a mk2 xr2i in my mk2 mex. There should be pre tapped holes in both the c pillar and the floor in way of the tunnel, and in the boot area under the steel parcel shelf. These holes are manufacturers approved fixing points for rear seat belts. Make sure you get the bolts with the rear belts as they are a special fine thread that is hard to get hold of. You also need the funny ally spacer/locator, similar to that fitted to the front belt reel. This goes to the new real in the boot. This is important as it correctly locates the new inertia reel in the correct attitude so the reel works properly when little load applied ie pulling the belt out to put it round the nippers but locks solid when pulled hard like in an emergency stop. If you dont have it set to the correct angle then it will not lock at all! I can post picks of mine if thats of any use, also i have spare ally spacers off the front reels if needed. Hope this is of some use.