Magnum 500 was a trademark of Motor Wheel, and the same wheels were used on many GM and Ford products under different names and of course bolt patterns.
To my recollection, most cars that came with Magnums still only had a steelie as a spare.
I had Magnums on my SeeDan, but I sold the set for $250 when I switched to 15's.
Old wheels;
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New rims;
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Why are you parked at a Ford dealer?