I dont see a broken mainshaft there.Or do I? Maybe I do.Is that a broken piece stuck in the yoke? I'd call PassonPerformance and see if he can get you a used shaft, and a new rear bushing, and a yoke. They are a cakewalk to swap out.
Does that tranny have a side cover? That would be the A-230.(the good 3-spd)
Or a top cover?That would be the A745
That looks like shock-loading, as in vicious wheel-hop?