I am also looking at the purpose of the bolt. The high torque figures utilized on that rear suspension are the nuts on the four main mounting studs holding the entire suspension crossmember on. I can see that need for higher clamping force there. Also, the three bolts holding that stud serve a slightly different function, have a 3:1 ratio there, and also go to sheet metal (well, a weld nut) not a large high grade stud.