* Convertibles are always rarer: Convertible versions of any car model are significantly less common than their hardtop counterparts due to higher manufacturing costs and lower consumer demand.
* Full-size cars in general were less popular in 1968: The muscle car era was in full swing, and buyers were gravitating toward smaller, sportier vehicles. Large, luxurious cars like the Fury III were becoming less popular.
* Plymouth's market share: While Plymouth was a popular brand, it wasn't as dominant as Chevrolet or Ford. This further reduces the number of Fury IIIs produced compared to similar models from competing manufacturers.
Considering these factors, a 1968 Plymouth Fury III convertible would be considered a relatively rare car. It's unlikely many survived in good condition today. You'd likely find far fewer of these than comparable hardtop models, or even convertibles from more popular brands and models of the same year. To get a better sense of rarity, you'd have to consult specialized Plymouth registries or collector car databases.
