It is not very likely that only the Fury's sill moldings needed holes being drilled, whereas the Newport's did not.
Apart from my gripes with V5X Vinyl Side Protection, also the M25 Sill Moldings have some inconsistencies. Bright sill moldings were a standard feature of the 1974 Gran Sedan/Coupe aka 1975-1977 Gran Fury Brougham and the 1974-1976 Newport Custom. But only on Fury fender tags they are listed.
It is not very likely that only the Fury's sill moldings needed holes being drilled, whereas the Newport's did not.
The Newports were assembled at East Jefferson, Furys elsewhere. So it could well be an assembly-dependent thing, a bit like the case of the L25 Trunk Compartment Light.
After nitpicking for a while, this stuff could be more serious: Belvidere uses two groups of 3-digits codes not seen elsewhere and for which the internet offers no easy answers.
In a slot following on the "Build For U-I-C" slot all 1977 tags have one of these:
000: PK41K7D
100: CP46T7D, DH23T7D, DH46N7D
101: PK41P7D
111: PM41J7D (2x), PK41T7D
222: PH41U7D, PK41U7D (3x)
And from 1975 on, right before the "END" code some tags may have another 3-digit code:
200: PK41U7D
231: PK41K7D
243: PH41U6D
262: PK41P7D
273: PH41U7D
281: PK41U5D
Here's an example showing both types of codes:
View attachment 271496
It would be interesting to know if these codes also appeared on the broadcast sheet, at the bottom, for instance.