They are both necessary

UPDATE---Success, or Close enough to it.

I posted a want ad on row52.com and a guy from Mississippi went to the yard in Alabama (which had '79 210 intact) and pulled them for me (including the washer resovoir and pump and a bunch of hoses) . I hope he grabbed everything I need, but either way its a really promising start. This cost me less than flying anywhere that had these cars in their yard anyway.

They're en route and should be here next week. Hoefully this saga will be over soon. My only concern is dialing in the carb after reattaching all this stuff. I may have to post here for help, but first will rely on the service manual which appears to have fairly detailed instructions.

Glad to hear!