There was nothing obvious when I got the truck a year ago. But I have been wheeling it since, and something must have done it, although I have no specific recollection of any particular obtacle or situation. I just heard a 'clonk' the other day on the Chiva run, the sound was strange to me, similar but not quite like a small rock being thown up, happened only two or three times, not enough to reproduce it and recognize. Did not notice anything then when I inspected the truck after the run (as it was getting dark).
I still shudder at the idea of what could have happened on I-17 on the way home.
For nursing it back from our last trailhead Tuesday and to Kevin's shop, Michael rigged two ratchet straps to hold everything in place, actually the crack closed a bit under that tension on the highway.