Sorry for the resurrection of a 6 year old thread, but some people may find this a useful read.
Had a good read of this and I have to say I'm still confused as to whether it's worth it or not.
Anyway I have a welded centre in at the moment and will have to find out the hard way, I guess the one thing that can be drawn from this is that they can be trouble for those who do not know how to drive them.
I'll let you know how it goes just waiting on a tailshaft to come back and we're all systems go....