Can I replace a Shimano RM30 8-speed freehub with an RM33 without any fiddling? I have a Trek 4300 mountain bike with a Shimano RM30 8-speed freehub that's slipping badly.  When I search for a replacement, some places seem to interchangeably suggest the RM33, but I was hoping someone could confirm that the RM33 is a drop-in replacement.  

(The reason I haven't just bought another RM30 is I can't seem to find an 8-speed RM30 replacement- perhaps the RM33 supercedes it?  I can't tell.)

Thanks!
The freehub should fit fine, the RM33 is for the updated/higher end disc hub version but it is backwards compatible to RM30.  Actual part# for the RM33 freehub is Y30V98050