Europe's Last Dictatorship
The POD here is that the Duke of Segovia doesn't renounce his claim to the Spanish throne, despite still facing pressure to do so on account of his deafness. Because of this, his son Alfonso is a much stronger candidate for the throne, and between this and other factors, Francisco Franco ultimately selects him to be King following his death, leading to the former's coronation as Alfonso XIV in 1975.
Alfonso is not Juan Carlos. He largely remains a committed Francoist, and while the first few years of his reign are fairly tumultuous as there's increasing pressure for Spain to liberalize, this ultimately subsides and Alfonso is secure in his seat of power, leading to a continuation of the Francoist regime to the present.
Spain ITTL occupies a similar niche to Saudi Arabia geopolitically; many people in the West are not all that fond of how reactionary and absolutist Spain remains, and while the National Movement (formerly FET y de la JONS) has
officially distanced itself from fascism, certain policies of the regime are a bit too close to that for comfort. Despite this, they remain a Western ally, still being members of NATO (although not the EU), and have largely been integrated into the economic order. Relations with the Vatican are particularly complicated; Spain is officially a Catholic nation, however, since the Second Vatican Council they haven't exactly seen eye to eye with Rome at all times, especially recently under Pope Francis' pontificate. Still, no official denunciations have come from either the Vatican or Madrid, and so relations remain officially cordial.
In 2005, Alfonso XIV would die of an illness, leaving his son Louis II to inherit the throne, being crowned on November 20 (coinciding, of course, with the Feast of Christ the King -
nothing at all to do with the anniversary of the deaths of Franco and Jose Antonio Primo de Rivera). Many were hopeful that Louis would oversee the liberalization of Spain, as in the past he had alluded to his support for a constitutional monarchy. These hopes weren't completely dashed - freedom of the press has greatly improved under his reign, as has freedom of worship - but overall most concessions have been largely performative, such as the decision to allow other parties to run in the Cortes. While this was permitted, the two other parties that won seats - the Christian Democrats and the Carlists - are more or less de facto puppets of the National Movement, and at any rate, they only comprise a very small minority in the Cortes. In fact, in some areas Spain has seemed to go in the opposite direction, especially economically, as after the 2008 economic crash and the economic fallout of COVID-19 Spain began to reemphasize their commitment to national syndicalism and self-sufficiency, working on removing foreign influence from Spanish markets. As the world's gaze has fallen elsewhere, it appears that Spain will continue down its current trajectory for the foreseeable future, much to the aggravation of the Spanish Republic in exile in Paris.