Welcome to the club.
These cars use McPherson struts up front
and Chapman struts in the rear.
Standard ( BASE ) suspension parts WILL all
physically fit / bolt on.
the aftermarket dosent offer any actual
" Special " struts or springs for these cars.
And Chrysler discontinued all of them a few years ago.
Alot of members here have been on the hunt for OEM
SPECIAL struts and springs for a few years now, and turning up
Your only choices are
( 1 )
( KYB EX-CELL-Gs seem to be the closest match ride / dampening wise )
re-use your original springs ( IF still in good condition )
re-use or replace the OEM front & rear upper mounts & bearings
( Use OEM ONLY ! )
re-use the OEM bump-stops ( if in good condition )
SPECIAL SUSPENSION requires SPECIAL bump-stops !
add aftermarket RUBBER or silicone spring isolators
from Monroe or Polly bushings.
I think OEMs provide a better ride, but they don't last
very long ( they literally disintegrate in 5 - 6 years or less ).
This is pretty much the closest you can get to
the original 300M SPECIAL suspension
performance, ride height & handling wise.
STAY AWAY FROM ALL QUICK STRUTS !
Every last one of them seems to have some kind of
issue or problem.
( KYB rear quick struts are known to make all kinds of
annoying noise over bumps,
and that gets worse in colder weather )
Monroe, Gabriel Moog and all other aftermarket front quick struts
are known to have upper mount and bearing issues
( they don't last like OEM, fail in a few months )
All quick struts seem to raise the car's ride height about
1 1/2" too high, making the cars feel UN-stable and top-heavy.
and requiring camber-bolts and camber-links to achieve correct
( even after they supposedly " settle down " after 100 miles or so )
The other option is
( 2 ) Have a performance suspension company CUSTOM MAKE high
quality adjustable struts / coil-overs and dial the setup in how you like
the car to ride & handle.
This option is VERY EXPENSIVE as no-one makes a performance coil-over
setup for these cars. It would be alot of money and trial & error testing
/ adjustments to get it right !
Sorry to be the bearer of bad news on this issue.
BOTH of my 300Ms have the PHG suspension setup
and those are discontinued too.
So Im kinda in the same boat as you.