i tried for a few weeks to source a clutch centre for the 6 spring and was told everywhere to avoid the ones you can buy now as they are rubbish
The probelm with my 6-spring basket when I got it was that the studs were not well swaged and, therefore, would turn when trying to thread on a Nylok nut. I brazed them all at the backside of the bsket and everything has worked fine. This, in no way, meant to detract from 4-spring versions. I just have no experience with them.
Richard L.