FS: W123 rear headrest kit
FS: W123 rear headrest kit
The mounting kit, complete: the four attachment channels, the two long seatback strut pieces, the four through-top-of-seatback grommets, and the two frames. No cushions. However, I'll throw in the W126 rear headrests shown in the picture--I *think* an upholstery shop should be able to make these W126 cushions swap right over. Or, you can take rear headrest cushions from a wagon. Or, if you wanted to be extra fancy, you could try putting bat-ear early W123 bamboo headrests on (I can sell you a pair for $50, shipped).
Note: I don't think you can just use the W126 headrests as-is, because the first bend on the W126's frame post is greater than 90 degrees, whereas on the W123's frame post it's slightly less than 90 degrees. But, I didn't actually try it.
$150 plus shipping, to anywhere in the lower 48.
The headrest posts and mounting brackets will work. But you'll need to acquire the two additional support braces as the w123's are shorter.