My 85 300TDT had that same material, as does my current 72 280 SEL 4.5. I agree with the post above. It's for sound deadening and to compensate for the difference between the height of the floorplan and the top of the air duct running on top of it. It's hard to find for my SEL so I'm not sure how lucky you'll be if you rip it out and then decide you want it back.

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-- Jason

1995 E320 Wagon
1972 280SE 4.5
1999 Land Rover Discovery Series II