David is correct. My '87 SDL and my friend's'82 SD came std with a bl. heater. The dealer had to add the wire at delivery. SO, look under the front (pass. side on my 603) lower side of the block and maybe you have one and just need to add the wire.

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Paul 1987 300 SDL; 2000 ML; '69 MGB; '68 VW Fastback