Retrofitting 126 rear headrests

[81Wagon]

I have a 1983 300SD with no rear headrests. Why anyone thought this was a good idea is beyond me. (I have one friend who refuses to even ride in the back seat lest we get rear-ended!)

I tried to search online but the only headrest kit I could find was for the 201 (190D/E). Is there one for the 124?

Alternatively (and cheaper) I have a 124 parts car lying around. The upholstery is a different color in the parts car so I don't want to just swap over the seat back (not to mention it's an SDL with a reclining rear seat so that's probably not possible anyway). Before I go tearing things up, can anyone tell me if the headrest mounts could be swapped from one seat back to the other?