Replaced both mounts. Driver's side was more collapsed than the passenger side but I think what really caused the hose to get sawn thru was the fact that the center inner metal portion of the passenger side mount has almost completely separated from the rubber. Under the right torque conditions I'm pretty sure it would allow the right side mount mount arm to rise up and the left side of the engine drop down, putting the PS belt on to the hose.

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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