Floor mat identification

[riv2x4]

Trying to identify a couple of Buick floor mats.  Black guessing mid sixties big car.  Only identifying numbers are Passenger side 9-63 date code 4239- PPI -P and drivers side no date code, 4374L-PPI-D7 guessing date code.  Black in color.

 

Any idea what they are for, the drivers side is not correct for my Riviera.

 

thanks

 

Larry

[riv2x4]

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