Why were the wagons banned?

Since the subject is A bodies discontinued after the 1966 model year, you may as well also consider that Valiant 2 door pillarless hardtops and convertibles were discontinued after '66. In 67 Plymouth moved the hardtop and convertible A bodies over to the Barracuda line to accompany the fastback and compete model for model with the Mustang. Similar things were going on at Ford and GM. Falcon hardtops were discontinued after 65 leaving only sedans, and for 68, hardtops were dropped from the Chevy II Nova line so as not to compete with the Camaro.
But, in Mexico, Plymouth buyers still only got the Barracuda as a fastback. The 2 door pillarless hardtop was still a popular enough body style for Chrysler to offer a hardtop on the redesigned 67-69 Valiant body. That Mexican hardtop Valiant would be another unique A body to have in the U.S. or elsewhere.

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