Help - Speaker spec on 90 SC bird JBL Subwoofer unit

 What is the speaker specifications for the 1990 Ford Thunderbird JBL Subwoofer unit with label  "E9sf 18c804ak Subwoofer 433m"?  I need to replace old speaker with new since foam has cracked and need to replace.   I need to know size, wattage if possible.