On May 20, 11:22 am, Wayne wrote:
Is it possible to replace the freehub on a 7800 hub to the 7850 Ti
freehub body?

Wayne

Nope. 7800 has bearings inboard of the FH body, Campy-style, but the
7850 is the traditional Shimano-style, with bearings on the outside of
the body.