Sloting seat runner to chassis mounting holes?

[davidimurray]

I've just fitted mine (Triton wide) and did it by making up blank rails. Getting all the seat runners fitted up to the seats. Then clamp some wood across the bottom of the car and lowering the seats into position on the rails. This then allowed me to move everything around until I was happy with the side to side position. I then drilled the rails and bolted the seat down. Then put it all back in the car and set up the rails for fore and aft position before tacking the rails in.

Personally I would avoid making slotted holes as if anything comes loose or relaxes in the future you will start sliding around. Also the IVA man might start to ask questions and think it is a 'bodge' rather than a deliberate bit of work.