I think the 2.7 Carrera was first circa '74 -'75. Then an option on the 2.7 911S. Standard on the 3.0 Carrera. By '78 I think it was standard on an SC and chrome look was an option. My '75 911S has black trim as an option.
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'75 911S Targa
'81 BMW Alpina C1 2.3