Some of us have been chatting about this exact subject.
Generally we feel the main threat comes from cast flywheels as opposed to the billet stuff we usually fit.
Having said that... for any-one like me putting a TKO ( instead of a T56) behind a holden/chev then check here for a steel bellhousing. Even if you want a LS to T56 steel housing.
http://www.quicktimeinc.com/products.html
Much lighter than many others and manufactured to a .0015 input shaft index bore tolerance.
Cheers