Broken Diff

I have only stripped gears in my 8n 3/4, and only 3 of those in the last 25 years. I was told that it was only because they were set up wrong(Iv'e never set a set up I don't know how). I think it's because I buy my 741s/391s/clutch sg out of 45 year old dodge trucks. I have never seen a broken pinion in any 8n 3/4. when I find a 742 489 I sell them because I trust the 741s for what I do, and people pay good money for the 742 and 489s. my currant car runs mid13s, but Iv'e had cars that ran in the low 12s with 741s.If you broke the Pinion can post pitcher of it, just so I can say I seen one?