I've replaced these heater blowers, first in my '72 250, 17 years ago and, most recently, on a neighbor's '72 220. It's a tedious job that takes about 2 days, without rushing. That first blower was $168, from Mercedes, but now it's over $400!
Unlike severe rust, for me a dead blower wouldn't kill a deal, but certainly use it for some serious negotiating.

Happy Motoring, Mark

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DrDKW