[Brant]

I haven't seen Joe's picture...
but the purpose of stiffening isn't to prevent full failure.
the purpose is to eliminate flex (that creates inconsistent suspension and handeling)

they put roll cages in race car for the same reason... not because the chassis' fails. because the chassis' flex

really only necessary on a track oriented car.

regarding the 901 transmission.
the actual cost/benefit ratio for failure occurs at 250hp when on a track

with track use the 901 holds up for an adequate service life at 250hp

but the 915 becomes cost effective above 250 due to the reduced service life of the 901 at that output.