"does anyone know what the white thing is under the drivers side rear seat? i think its the power antenna motor but im not too sure i have to double check it"

ditto!

Sorry for bumping an old thread, but this is the only reference I could find after searching. There's no part number on it, and mine's disconnected. It looks like a vaccum accessory, but there are no lines on it, just a 3 pin connector.

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1987 300D - Frybrid - sold
1985 300SD