breaking lower a-arm u-bolts

[Idaho68]

Was at work tonight and my wife called, saying her truck (68 GMC half ton) had broken yet another set of those silly u-bolts that GM used to retain the lower a-arms . I popped by the shop we take it to to look at it after work and sure enough, same bolt, same side as last time (about 5 monts ago). Now, I know how she drives, and I do think that is the issue, so what could be causing it? Not that it is gonna make a difference for this truck, as we both agree that without a place to restore it, or the time to work with it, it is going to have to find a new home to make room for her next vehicle, but I would like to know where to look for my next one.