According to the 70 Camaro AIM (UPC 12, sheet A8) the horn relay installed on the assembly line was GM # 1115889. My NOS 1115889 horn relay (in an old "string" box) is stamped "889" with a line underneath on the bottom and the mounting bracket is made of black plastic. Was the mounting bracket on the assembly line 1115889 horn relays made of plastic or steel? The metal cover is metal with "Delco Remy", "MADE IN USA", and 4 letters in the corners ("S", "H","H", and "S"). embossed on the top. My 1970 Chevrolet Parts Catalog (effective Jan. 1970) lists GM # 1115890 as the horn relay for all 1970 models and this part number is exclusive for 1970 models as per the asterisk. According to Chevrolet Parts History GM # 1115890 was replaced with GM # 1115889 in June 1971. This is a bit confusing.