The Bilstein B6 Performance rear damper is a 46mm monotube unit built for the rear of the 300. Its job is to work alongside the factory coil spring rather than replace it, and its application specific valve settings are tuned to this platform's handling. Search terms buyers use include "B6 rear shock 2005 Chrysler 300 RWD," "Bilstein 24-144780 monotube," and "300 RWD rear damper upgrade."
On other platforms, owners on user forums report about 12K miles on B6 units with no leaks, and say the rear feels definitely firmer than stock, which they consider a good thing. That is the case for paying more than a budget replacement: a gas-pressure monotube is meant to hold its damping feel over time, and it avoids the multi-bounce behavior that owners describe in worn stock dampers. Fitment varies across sources, so confirm the application with the manufacturer before ordering. The part is one rear damper, and the listed extended length is 24.83 in with 5.54 in of travel.
This part is listed for the rear of the 2005 Chrysler 300 RWD, but sources disagree on the exact year range and trim coverage, with some listing 2005-2010 and others 2004-2012 with trim notes. Confirm your VIN and trim with the manufacturer before ordering.
No. The part is designed to pair with your factory spring, and no spring seat is included with the damper.
This is a moderate DIY job that mostly requires a floor jack and patience. One owner used a floor jack to compress the shock after installing the top, to get it into the lower seat. Owners on user forums on other vehicles also describe gas-charged units as needing to be compressed with a jack during install. Expect the top nut to need a second wrench to keep the stem from spinning, and expect the lower eyelet to take some wiggling to align. Check the factory bushings and washers before reuse, and torque the lower bolt to specification.