Motor Wheel also sold Magnums to the public like other wheel maker. I don't know if they did a 5 on 4 bolt pattern but the centers on the wheels on the Dart in the pic look like the "aftermarket" centers. I don't think any manufacturer called them "Magnums" , , , *PIC*
Chevy called them "Sport wheels" when they used them on SS equipped cars in '69 and Olds called them "Super Stock II"
Someone needs to send in the 50 cents to get the catalogue and find out. LOL