In the trunk of my 240D---near the clip that secures the jack--- there is a round indentation, with a sharp point sticking up in the middle. What is it?

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1977 Mercedes 240D. 4-speed transmission. Windows, A/C, and sunroof: all manual. Medium Red. 204K miles.
1988 Subaru GL wagon. Dual range 5-speed 4X4. Daily driver w/ twin parts car.
1994 Subaru Loyale wagon. 5-speed 4x4
1966 International 3/4 ton 4X4 truck. Ooh yeah!
1952 Ferguson TO-35 farm tractor.
1984 Snapper rear engine riding mower. Just like Forest Gump.
1988 Nimble 20 sail boat
--Older stuff is built better--

A photo would help...

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012