I just bought a pair of the entire assemblies. Didn't have a manufacturer indicated but they were listed as OEM and the box had a Mercedes logo on it. Much less hassle than unclamping and unscrewing the old greasy, dirty units and reassembling. They were only $25 or so each.

Edit: Oops, sorry I just noticed it was for a 190. My comment about pricing might not be relevant.

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1983 CD
1958 Studebaker Packard (being resuscitated)