https://www.*******.com/products/mercedes-engine-piston-w-rings-240d-300cd-300d-300td-6160306417

I would contact them and ask where these are made. They are great to deal with and offer lifetime warranty which I am sure you don't want to take advantage of.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked