I just think it's funny you guys always wanna push what YOU think is right without any data to prove it... You guys are the joke and the ones not offering more than one option... Both are fine 8.8 in the long run is better if you find a good one at a good price but it much easier and safer to just stay with the 7.5
Where is YOUR research that validates the 7.5 breaking before the 8.8? I guarantee you a high mileage 8.8 will break before a lower mileage 7.5 with the same rear diff gears. It's just what makes sense. I personally would not take the risk of buying an 8.8 rear end I know nothing about(as in how it was treated) off of someone or a salvage yard, especially if it came off a vehicle with high miles.
I generally don't research things I know to be true, but to answer your question, the evidence is everywhere. I've seen the 7.5 called a ticking time bomb. It is general knowledge. You just choose to ignore it or are too lazy to research. My first Google hit was Wikipedia: "It [8.8] was also used in the 1986 model year V-8 equipped Mustangs, replacing the weaker 7.5 rear end." http://en.wikipedia.org/wiki/Ford_8.8_axle
Need I research further? This argument is stupid, but hey, go ahead and recommend the 7.5, as long as it's not to me or my friends. Then again, my friends already know better.