Is it safe to assume that the speaker grille back frames with threaded studs/nuts on the back were on cars with radios, and thus speakers behind this grille, AND the long dash piece would have the four holes for attaching the threads to the actual speaker....and ones without, and with no holes in the long dash wood piece were cars that had no radios/speakers? I've seen several, and it seems that all of them have the countersink holes for the studs, some have them, some don't. Same with the long dash piece as to four holes/not.