The 108 rear suspension is neither truly independent nor solid axle. It's a swing axle setup with a central compression spring or hydropneumatic compensator. I believe the issue Frank is referring to is that a sway bar would link the wheels, causing the camber change that helps handling during heavy cornering to not occur, and thus having the opposite of the desired effect. If you plan on converting to a solid rear axle or a true independent suspension without the central spring, such as modifying it with a 116 rear setup, then you would benefit. If you plan to do an air suspension setup on the car, and eliminate the center spring, it may help or it may still hurt with the given 108 geometry. I believe, though, that the 109 had no center spring and did have a sway bar.

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2021 Charger Scat Pack Widebody "Sinabee"
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1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k