That rubber port in the firewall is right in front of the instrument cluster in the dash. If your tach and clock were transparent, you would be looking at the back side of the rubber plug.

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John

2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)

Click to see 87 300E