I performed this upgrade on Coda and have the parts for the 87 Champagne. Here's the write-up done by Chad:
http://www.peachparts.com/shopforum/diesel-discussion/287882-brake-light-upgrade-w123.html

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daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
No longer selling Cluster Needles Paint
No longer selling New Old Stock (NOS) parts

Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more