But while you wait for the new heater core, It is time to remove the front carpets and clean them. The only hassle is removing the two front bolts that hold the seat down so you can slip the carpet rearward a bit to clear the floor heat vent.

I washed the carpets in my bath tub, it had a flexible shower nozzle attachment. I used simple green and a large bristle brush, being careful not to bend the fiber glass backing. The slope of the bathtub was the same as the slope of the carpet. And then let it air dry for a day or two.

The rubberized padding is one piece for the entire cabin and cannot be removed. If antifreeze got under the padding, you will need to find a bunch of black & white newspaper to shove under the padding and absorb the antifreeze. This may take a couple of days, and LOTS of newspaper. You can still drive the car, if you bolt down the front seats.
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Keeping it running is better than buying new