I think the purpose of the rubber grommets is to isolate/dampen any vibration from the engine to the body. Will those dampen the vibration or transfer it?
Karl, they are solid , but they are absorbing. as you mention , they were put into service to isolate the suspension from the body for a smoother/quieter ride . i know that in 75, the rear springs are also isolated with rubber from the axle perches/shock plates, im not positive about 74, but my guess is they are. the new ones i bought are harder than the originals, but my charger rides like a cadillac with them lol. the torsion bar crossmember is also isolated. 1973 brought the changes to the B Body suspensions. i never took note of the rear ends on my 73 and 74 chargers