Replace your mounts with lemforder or phoenix brand mounts only. Then make sure to replace both hoses, you take a big chance trying to take the nuts off the cooler. Here's a write up I did when I replaced just the hose portion. I would also replace the trans mount while I was at it.

http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1795649-oil-cooler-line-rubber-replacement.html

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