Just to be sure we are talking about the same thing TD=Station Wagon not turbodiesel.
The station wagon has hydropneumatic suspension in the rear which virtually no diesel sedans had. It should be checked for functionality because some parts are extremely expensive if missing or broken. Pump is about $1200 for instance.
The transmission on 85's is controlled somewhat differently than earlier models. It has the 'blue flying saucer' in the vacuum system to improve shifts and has an electronic rack sensor which has something to to with the EGR.
Is the 85 the only year of the 123 with a Klima in the climate control system?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13