energy suspension makes bushing inserts.
and you can get solid bushings from pdm, they are a major pain in the ass to install though.

something might not be installed right, becasue the spacers basically isolate the bushing, and make it as though there isnt one there.
but there will be more noise too with spacers, because the bushings take up alot of abuse from the diff, and now those arent really there anymore.