The Chrysler Road wheel (15 slot W23) had 2 iterations:
1970-1978 15x6 (actually, I think they are 6.5 in width, but I haven't measured on in ages...anyways). Used on our beloved C bodies, B bodies and even the fancier light trucks.
1978 Transition year. When the C body NYB Salon Aluminum fascia road wheel appeared, the road wheel shifted to 15x7- yes underneath the aluminum finned aluminum fascia basket was a black painted 15x7 road wheel.
In 78 the chrome road wheels were still 15x6.
From 79-81 the steel Road wheel manufacture is standardized to 15x7 and were M body optional offerings and 15x7 chromed again like the previous years- still black paint under the Aluminum fascia road wheel which soldiered on as a B body option (most often seen on Dodge Magnums).
1979 Chrysler Corp. really pushed their new forged aluminum rim offerings and the steel road wheels vanished from the dealer data books, but they were still available, notwithstanding.
The 15x7 "M body" road wheels are far more rare than the C body narrower variety...but they're out there.