Do you feel lucky? Lots of driveline failures only take out the drive part that breaks.

Or maybe the 8-3/4 breaks, damages the sprague, maybe you grenade a drum in the trans? Or maybe you bust the little U-joint and tear up the bottom of the car? Or maybe the rear end locks up solid at speed and you loose it and hit a tree? There's a lot that can go wrong.

So it all depends on how lucky you feel. Me, I don't like to trust luck. I'm not a worry wart at all. But some damage can't be repaired. So I always get the good stuff for the driveline. Do C, or at least B, but not A.