As most know, this is when the CD's and Socialists evaporated in Italy in the early 90's. Why? Heroic judges unearthed decades-old ties between both parties and the Mafia, as well as numerous more mundane political scandals. This led to "Berlusconi or Communism", and his subsequent installation as defacto PM-for-Life. Let's say some pols decide to use Marcos-style extrajudicial powers to eliminate these heroes. As the Mob did themselves, with some cities resembling Civil War-era Beirut, and numerous assassinations of politicians and judges. Would it surface eventually, and how would the scene change? Would Berlusconi lead the CD's to the right?
Not at all !
Tangentopoli wasn't -mainly- about Mafia : focus was on bribes on local levels, with enquiries moving further to the top as time passed.
Without Tangentopoli (which didn't require a civil war not to happen, it would have been enough that Mario Chiesa, the first socialist convicted for corruption charges, stayed silent, as did the post-communist Primo Greganti, with the Party providing for his post-imprisonment financial conditions) ... well, things would have been WILDLY different.
The Socialist Party may have annexed bot the smaller Socialdemocrats and the post-communist Party of the Democratic Left, thus rivaling in numbers the Christian Democrats. We would probably see a further growth of both the Northern League and Orlando's Web (La Rete), protesting against CD's corruption.
BTW, Berlusconi at the time was closer to the Socialist Party (yes, we created a monster

): however, if the system stay strong, he wouldn't enter politics.