2002-2004 DCCD has a suretrac front LSD
2005 DCCD has a torsen helical but still retains the 35:65 DCCD.
2006-2007 DCCD has torsen front LSD and 41:59 DCCD
2008+ is the same as 2006-2007 but it has no speedo drive and no internal oil pump.

2001/2002 wont require front stub conversion. 2003 onwards requires it. But its not difficult or really expensive to get stubs and seals so dont worry about it too much.

Your current 5 speed clutch, flywheel and starter motor is bolt on for a 6 speed gearbox. No mods required. The only thing is you MUST use the 6 speed clutch fork with the 5 speed clutch/flywheel setup.

Once you buy a 6 speed and a cusco tarmac center diff. With the cost added together, you may was well get a DCCD 6 speed. You dont have to run the DCCD controller right away.

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RS Liberty - Because WRX's are only good for parts...