Ugly rumour, again. The diffs should have had an initial oil change after about 1000 miles I understand, which sometimes wasn't done apparently. Beyond that however the oil change is at 150k miles, or 10 years, whichever is sooner. I don't call that a "fairly regular schedule" ! Mine, which still runs perfectly and no whines or clonks, was changed for the first time at 200k miles when I acquired the car. Using the correct oil is absolutely imperative.
I don't know where you are getting all this fake news from, but I think you should really change your reading habits!
When/if you finally do buy a 260, and become a full member, you will find lots of reliable information here to help you along with ownership, of course.