The shape may be the same, but the diesel tanks have fittings for the return line. I bet thats why the part numbers are different. If you can get a tank out of a gas car cheap enough I would compare them and see if you can safely make it work.

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2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200