I wonder if the later "500" OD trans has the same bushing.
Maybe a later year 904 application than your car would still be on their files?

If the bushing is bad, it may be the cause or it may have been caused by the vibration elsewhere!

U-joints worn
driveshaft dinged/kinked
pinion angle off
trans mount worn
lost balance weight off driveshaft or wheels
???


moparts does have some transmission people/businesses who should be able to supply one or advise more.