You don't just remove one side of the case it splits and all the inners must be removed in order to get it to split. Its the same as what you would do to replace a crank for the most part, except you are replacing the shift shaft...
2004 400ex: Hot Cam, HMF S/O, K&N & Outerwears, Eberle Scoops, Pingry Oil Tank, AC Nerfs, DG Bumper, Swinger Skid, Homebrew Body Skid, Homebrew A arm skids, MSR High Bends, ModQuad Block Off, Ohlins Front Shocks, Dual Rate Rear Conversion, Durablue Lowering Strut, Pro Design Case Saver, Razr's F/R, ITP Baja's Rear