If you own a pre 2007 OS alloy axle Campagnolo hub (Chorus or Record) then you have a circular 17mm OD axle which means the current FH-BUU015 for Campagnolo or BUU015X1 for shimano freehub body won't fit. Incidently if you have a Centaur/Daytona hub you need the FH-BUU015(X1) freehub body.
So the current FH-RE415 freehub requires you to change the axle. The kit has the current 3 lobed axle and an FH-BUU015 or FH-BUU015X1 freehub.
You have to use the supplied axle but once fitted the hub is restored. 11 speed compatible as well.
Once you have fitted this kit all you need in the future is the current oversized axle freehub in future.
While Campagnolo don't sell the shimano version of this kit I will replace the campag body with a Shimano one.