Which is True? 26 or 41?

The New Testament was issued by the Catholic Church. That’s infallible. Or inerrant, if you prefer.

All the Ecumenical Councils are infallible.
The extraordinary Papal pronouncements on the Marian Doctrines of the Immaculate Conception and the Assumption.

I think you might be confusing the infallible Doctrines of the Catholic Church, which is basically everything that has been carried forward from the Apostles with those last two so-called “extraordinary” pronouncements.

The rule of thumb that I follow is that everything the Catholic Church Teaches officially, is infallible.

for more info,see this site. Here’s an excerpt:

To the first category belong “truths taught as divinely revealed.” Some theologians call these truths “infallible dogma” or “definitive dogma.” These are truths contained directly in the Word of God and which the magisterium has affirmed to be divinely revealed. They are infallible and, to them the faithful owe the “obedience of faith”[7] or “divine and Catholic faith.” This second formula is found in Vatican I, which taught that both the Extraordinary (or Solemn) magisterium and the ordinary and universal magisterium are instruments of transmitting infallible dogma:

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