how do you remove the rear leaf spring bushings on a 2001 jeep cherokee

my rear spring shackles both broke and I'm trying to remove the bolts and bushings to install all new hardware, but reusing the old spring packs. I've tried mystery oil, drilling out the rubber bushings with drill bits and carbide burrs - there is very little room to work so its difficult to push the burr all the way through the bushing - short of burning them out with a torch - is there a solvent like acetone or methyl chloride that will work - I don't know what kind of rubber the bushings are made from but it sure is tough stuff.
Help....?? Thanks