If it is a 300D from the 1980-85 there is several long threads and a bunch of choices.

But, before removing the Oil Cooler Hoses from the Oil Cooler you ought to read up on the few ways available to keep the Hose Nut from stripping the Aluminum Oil Cooler Threads and also note that there is a repair if that happens.

That happened to me on one of the Oil Cooler Nipples.

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84 300D, 82 Volvo 244Gl Diesel