Replacing the fan hub and drive on 4104

[luvrbus]

Ok I have all the parts from a RTS belt driven fan drive I am going to help a friend replace the god awful fan drive on his 4104 that keeps throwing the fan into the radiator ,it looks fairly straight and easy has anyone here done it. 
I never used it before but I have done the pillar block bearing,shaft and pulleys before as a replacement a lot of work ? what are the pit falls nothing is ever as simple as it seems 

thanks

[Hard Headed Ken]

Clifford,
Do you mean the mutiplate wet fan clutch?

Ken