This text is simply to thank everyone who helped me by bringing new information, dodging inaccuracies even coming from me, through the language and the lack of knowledge about the subject. You are amazing! So amazing that you answered my question precisely, taking into account characteristics that, if I were to write the topic today, I would try to eliminate using a few more restriction filters. Even limousines were taken into account, and I, laughing, was forced to think "yeah, they're absolutely right. I didn't say I didn't want limousines to be included as results." I'm looking for "ordinary" cars, not including ambulances, funerary cars, limousines or special cars (but it was good not to specify. The reason is in the penultimate paragraph). If I were to make the topic today, it would be more objective: with my desire to buy a miniature (1/12 or 1/18), I wanted to choose the biggest car of that period, with ltailfins and that had already been reproduced in one of these scales. But at that moment, I thought that asking the way I asked would give me more chances to meet other models, regardless of whether there are replicas or not. I also thought this would over-specify the question. Today I think this information would simplify it, save confusion, and even allow me to specifically filter on "biggest convertibles with tailfins" if none of the common options suit me.
However, I send this text only as a thank you and also a satisfaction, without wanting to propose other questions. I know that there is a part of the forum dedicated to scale models and it is not my intention to change the difference of this topic either, but joining a little of what I knew with some information brought here, within the "biggest cars with tailfon ever reproduced in miniature" what else might please me:
1 - 1961 Lincoln Continental Ss 100 X (1:18)
2 - 1958 Lincoln Continental MKIII J.F.Kennedy (1:18)
(these two options I would never have known without your help or if I had written the text in another way, excluding limousines. In the end it was all worth it!)
3 - 1961 Chrysler Imperial Crown Convertible (1:18)
4 - 1959 Eldorado Biarritz (available in both scale)
It will now be up to me to choose between options that I like the most, such as knowing if I prefer a larger car on a smaller scale and other details such as color and level of detail. Thank you so much again, I apologize for any ignorance or inaccuracy. I also hope I have clarified some more details and even though it's not a topic with new questions or requests for help, any contribution will still be welcome!