Originally Posted by SamS
That broken fin on your diff is cause enough for alarm right there. Those things just don't break off. Something impacted the underside of the car, and the proximity to the failed part would leave any ration person with suspect.
Sorry, what are you talking about? Did you look at the pictures? There's no broken fin
. There is slight abrasion maybe 1/8" of an inch in area to the aluminum that resembles pitting from small rocks, e.g. normal wear and tear. All the fins are intact, but you can't see them, the picture is from the side.
The diff cover is made out of soft aluminum. No rational person would conclude some abrasion to soft aluminum would be responsible for the break of a steel high-tensile strength 10.9 bolt.