He want's the hose that would be the same at number 257 in this diagram. I say, would be, because for the manual climate system, I think there is another curve, as the one end goes to a stub coming out of the firewall, where as the hose in this diagram connects to the pipe that is mounted to the firewall.

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1983 W123 300TD US spec Turbo engine, with Euro bumpers and manual climate control, and manual transmission.