My old body had at least 50 extra holes in the body and was basically wasted beyond repair (sawn out wheel arches, etc) - so I bought a new body from Tony Thompson. So I had no holes to guide me either. Just position filter as far to the left (looking at car from the front) as you can, without hitting the 4" flexible ductwork or the headlight pods (move them thru their arc of travel). Then move backward toward the steering rack and you’ll see you can only locate it within about a 2" circle - as I recall. My next project will be to block off all areas around the radiator so air HAS to go thru it - not around it. Good luck
Paul Zimmerman
65 S2
My '69 S4 FHC SE had the airfilter in what I think was the original position, 45? to vertical and plumb in the middle of the car, right across the radiator air-flow, so as the car was over-heating I moved it to the far right of the car, exactly as per “brassrngfm” 's answer, and kept it in a horizontal plane, the twin tubes pointing at the grill. I also fitted the blanking panel (from Sprints I believe) over the steering column, the foam on the bonnet over the radiator, and drilled the two holes in the left-hand inner wing (as per the Factory Workshop manual…). Together these have cured the overheating, even here in SW France. I think each step only did a little bit, but together it’s enough to make a real improvement. Hope this helps, Tony.