It seems I did a bad job tensioning the alternator belt after doing the fan clutch and thermostat at IDIBRONCO's place. It got thrown today. I don't think I did it my usual way, and in almost 3 years of IDI ownership, it never got thrown before. Too many cooks in the kitchen so to speak with him there too. Not blaming him, I just don't do my best work when distracted. Thankfully it didn't take out any other belts nor did it get caught in the fan. It's just completely gone. It did knock the alt/vac pump belt off and flipped it inside out but it was there pushed beyond the pulleys. Only odd noise I heard was a once I heard a sort of thump when driving on a 30 mile stretch of rural highway with pretty much nothing along the way, but nothing that sounded like a disaster. I did notice recently that the belt seemed awfully loose, but then my crap memory made me forget to go back and tension it. I have a spare 9580 belt, so I will be putting that on in the morning. I was able to limp to a truck stop about 5 miles beyond realizing I had effectively no brakes. I have to let it cool off first, so I'm at a truck stop for the night. I want to get my hands on two more of those belts, since power steering uses the same one. That way I have two spares in case all belts get destroyed. Oreilly has their 9580 Masterpro belts for $7/each, far cheaper than Gates XL at $28/each. But are they any good?