My car did that vibration a while back was worse in drive also. Real bad at 65 mph+. Eventually, rebuilt my 440 sixpack due to other reasons. Replaced 35+ year old at that time damper with a new Pioneer damper. All vibration is no gone. Rubber was shot in the old damper.
1963 Belvedere 440 Max Wedge Tribute
1970 Charger R/T S.E. 440 Six Pack
1970 Challenger R/T, 528 Hemi
1970 Charger 500 S.E. 440 4 BBL
1970 Plymouth Road Runner 383
1974 Chrysler New Yorker 440
1996 2500 RAM 488 V-10 4X4
2004 3500 Dually Cummins 4x4
2012 Challenger R/T Classic.
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