Though there were some mid-1930s exceptions, through the 1950s an American brand's grille design was used for all of its various models from entry level to the most expensive car offered. This was because those models usually used the same basic body. (General Motors' Oldsmobiles and Buicks often used more than one of GM's A, B and C bodies, but retained the same basic grille designs.)
Then around 1960 Detroit's Big Three carmakers introduced "compact" and shortly later "medium / intermediate" bodies to supplement their "standard" body lines. At this point, brand continuity began to suffer across sub-models as well as over time.
The present post presents grilles used by the Ford brand for model year 1972, where thematic variation was considerable.
Unless otherwise noted, images below are of cars for sale or whose primary Internet source was unidentified.
Bunkie Knudsen, who favored prominent "noses" on cars.
In some respects, these various Ford models might as well have been separate brands, because they functionally were such. But to make that official would have required legal/contractural steps regarding dealers as well as expensive signage, plus likely additions to the corporate bureaucracy along with possible hiring of more advertising agencies. Calling these diverse models Fords kept things simpler, and the general pattern holds today for most automobile manufacturers.