Perhaps a clue from my Paul A. Herd restoration guide.
Quote:
Plymouth, 1968: A vary popular option was the sport wheel option coded 583. This was Plymouth's equivalent of Dodge's mag-style cover. Listed as part number 2881773, it can be recognized by its use of a center dome and five slots cut into the outer edge.
Plymouth, 1969: The dealer-installed mag-style cover continued unchanged but was canceled shortly after the start of production due to lack of interest.
That "Guide" is full of un-facts. And isn't a guide for much of anything.
