For the life of me I cannot imagine why The Summit damper didn't work. It looks to be counterbalanced the same way and only one application for 1971-1992 Dodge 360. All I know is it looked great, ran straight but my problem was not resolved until I rebuilt and installed original damper. Stock has weight removed for proper balance, Summit instead has weight added to opposite direction and side. Can send you detailed pics of damper if you like (autoxcuda) Tried to post pics, didn't work.

As for as poly mount I do plan to reinstall and see if it does indeed magnify vibrations. The poly mount looks to be much more heavy duty. Will take a week I am out of town


As for pinion angle it may help (my car is lowered) but my vibration was consistant whether in park/neutral or driving