I got a replacement from Larry at Alfa Parts Exchange (APE) Alfa Parts Exchange - Used Alfa Romeo Parts. If I remember correctly, S3 will also fit your S4, just the tool is different to tighten and loosen. S3 uses a hex and S4 uses torx. I am not sure of other years.I have discovered something else, the bolt? in the front of the camshaft cover, is stripped. are they easy to find? can I repair this? 1992 spider
Great job on the airbox! That was the next project for mine. You beat me to it!