From.... http://www.subaruwrxparts.com/05legacy.html
http://www.subaruwrxparts.com/photos/ksb751.jpg
Whiteline Differential Bushing Kit
The rear differential bushing kit is designed to lock the front of the rear differential support outriggers to where they meet the body. Fitting of the kit will reduce rear-end float, particularly under acceleration, and will help remove the "thump" on hard/quick gear changes.
$30
http://www.subaruwrxparts.com/photos/kb003diff.jpg
Kartboy Rear Differential Bushing Kit
The Kartboy differential bushings reduce the compliance of the rear differential, helping to eliminate the "bang" from the rear end on crisp shifts. 6 piece set, black urethane.
$32
Yes... these are for an '05 Legacy GT. So... who's first?