I had a similar problem on my 85 TD. It was dry half shafts and maladjusted SLS holding the shafts at an unusual angle. Check to make sure your SLS is holding the car level and then pack the half shafts boots with the correct grease. Solved it for me. (StarTech in Denver diagnosed it. I thought it was a wheel bearing).

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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