I would consider those the extreme cases. 10in lower on a 2.8KB is really pushing it.
Also the 3.6L KB doesn't require the spacer of the 2.8L so even though it did break, I don't think the spacer was the cause.
I am not saying it can't or won't happen but it doesn't happen to every truck.
A 3.6 KB does require spacers, about 1/2" whereas the 2.8 requires about 3/4". So not as far, but still spaced out further than 0". JL has new midplates though that keep the big blowers in alignment so no spacers are required.
Also, how the alignment key for the balancer (point of failure on the first link) is machined/ cut causes a significant stress riser if the key is supporting the rotational load. This is typical in the way keys are cut and this can be improved upon easily with a little extra time and small die grinder with a carbide bit. The clamping force and surface friction of the balancer to the crank should be what supports that load, not the key. If the bolt is loose or nor properly torqued or the contact area is reduced then the key will start providing the support (something it is not designed to do). Even reusing a bolt that has been over torqued or stretched can be a factor in reduced clamping force.
I do 100% agree with that, it's not one factor alone, it's a combination of them. In Carmelo's case, examining the broken crank snout up close, it appears it started as a stress fracture along the line of the keyway because it was only a single key. If it were double keyed I think it would have survived longer. But having things extended out is putting additional load on the crank snout, which is accelerating and increasing any stresses on it making it more prone to a failure sooner.
All I am saying is that a I don't think running a 2.8L with a spacer will automatically break the crank. Pushing the hp envelope to the extreme obviously increases that risk but that goes for any blower.
Correct, running a 2.8 with a spacer wont' automatically break it, but when you do push it, a 2.8 with spacers is more likely to break a crank than a 2.8 with the new midplate that doesn't need spacers