I had a Dana 80 in my last tool truck. Not as tough as my Rockwell's in my other trucks. In 28 years, 5 trucks, and 850,000 miles, the Dana is the only one I had to have rebuilt.
Heck man, I'm impressed with my little 7 1/4 in the Valiant. I've seen them broken before, but how many millions didn't break? I have at least one. 58 years old. How many miles might it have on it? I've had it apart twice. Once to inspect it and replace seals and the second time doing the rear axle swap cause I was too cheap to buy gear oil. lol Both times it' still as tight as new. No play anywhere. People can ***** about them all they want. I'm impressed.