Another "what's the difference between"

blu340dart said

Years ago I purchased a set of 15" ford magnums that were off a friends wrecked mustang and the center hole was smaller and wouldnt fit over the hub center of my Challengers disc brakes. That would be what I would look out for when buying the ford wheels.

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I was trying to find a way to rebuff you, but IIRC you are correct- there were two different size center opinings.

Not the "register" that everyone knows is on a plain steel wheel, but the actual hole for the center cap on a Magnum 500 style wheel.

In the ford catalogs they list center caps for two different size holes.

My theory os that if the wheels have the same center cap as Mopar wheels, you are probably OK.
If they have the shallower "push-in" style cap---better check the hole diameter.