As noted, the first-gen W23 Class II 16 Slot Road Wheels were all 15x6 wheels. The trim ring was squared-off with a concaveish inner section which met the wheel at the chromed slot area. Same wheels were on the '73-'74 Satellites, as a part of the Radial Roadability Package with GR70x15 Goodyear white letter radials. These first-gen wheels were not that popular, for some reason. Possibly a little plain in comparison to some of the fancier wheel covers of that general time?
When the '75 Cordobas hit, that's when they tended to be "everywhere". As noted, the shorter and smooth center cap assemblies. Same squared-off style trim ring, as I recall. Many New Yorkers had them, too. Still 15x6 sizing.
The trim ring pictured in the OP's picture is an aftermarket ring, not a factory item.
There was a 15x7 version that was on the '77 Chrysler LeBaron cars. Not very many of them, either, by observation. Some had a body-color ornament rather than (or assembled over) the silver painted area of the other W23s, except possibly for the SFGT cars. Wider trim ring to match the 7" rim width.
The observed issue I had with the W23s on my '70 DH43 is that the bolts which hold the center caps to the wheel, from the backside, would get loose and the caps would rattle as the wheel turned. The pot metal in the base of the cap is somewhat soft, so easy to strip the threads. OEM uses a special "screw" with a copper washer. Getting it just tight enough, but not too tight, is the trick! Especially on a used cap! The OEM bolts are self-threading, with a taper at the end to assist in self-threading a new center cap.
IF a normal bolt is used, they usually are a hair longer (and not tapered at the end) and will put a dimple on the outside of the center cap base, because of that.
As much as I disliked the exposed bolts on the similar GM wheels, never a problem with stripped threads (as the bolts screwed into the wheel itself) or rattles.
Enjoy and Happy Thanksgiving!
CBODY67
