I have seen many members on here with those gauges in their '05 legacy. If you google search you can come across several threads about this on here. Search STi gauge cluster legacy gt.
If interested in buying one, you can basically get a new one for the same price as a used one here:
http://parts.subarupartswarehouse.co...subcat2=136848 (
Applicability: Legacy 2.5 GT and Outback XT (2005-2009) w/o NAVI.)and here is the thread where I found the info
http://legacygt.com/forums/showthrea...ck-194337.html
*edit...well crap, looks like the price is more now. Maybe call them and see if they'll discount it.