[peterpjb]

this warning seems comprehensible to me in the first place,

but... I am involved in vintage and race cars for about 30 years especially alfa romeo and have never heard about such an issue before,
e.g. the giulietta SZ or TZ has also aluminum body and propshaft tunnel, with engine, belthouse and trans also out of alu, they are reving in the races up to 8.000 and 9.000, never heard about any failure of flywheel or clutch that caused damages, and many many of the other 50th and 60th racecars are driven with aluminum bellhouses, the majority even has no alternative between alu or steel

the only fear according to drivetrain-damages I know is about a detached propshaft, but that can be solved with a propshaft-cage

are there any documented destructions of an aluminum bellhouse and injured legs caused by a flywheel- or clutch- failure?