The car is worth the asking price for the interior headrests alone.
I've seen similar rear AC in only two other Mercedes, a W108 sedan that was a Japan import and a W111 US Fintail that I own.
Rear AC was commonly used in high-end cars that were not well prepared for dash modification, including Jaguar, Rolls, Facel Vega.
I think the 1956/1957 Lincoln Mk II also had rear AC.
New add-on kits for rear AC are available on-line. It's a good match for some cars that have little to no under-dash space. I'm considering it for my Alfa GTV.
I hope to resurrect the unit in my Fintail but it's not at the top of the resurrection list...
Scott