Go to a chassis builder or fabricator/welder, they will make and install what is needed. You could do much of the prep work by removing seats, console and carpet.

Unless this is a show car, searching out an OE replacement part is respectfully a little "over-the-top" and could make the difference of whether or not the car gets back on the road.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer