The two rear diff mounts that go into the subframe are best replaced with the factory tool or equivalent. ($100 from Baum or PerfomanceProduct.com). They are a very tight press fit. Some have reported success cutting them out with a torch, or cutting one side thru and then beating them with an air hammer. Be careful as you can damage or distort the subframe. When installing note that the bushings are not symmetric, there is a top and bottom. Factory procedure is to use a jig to 'square up' the diff such that the left and right bushings may not be installed the same exact length into the subframe. Some just install the new bushings with the same length exposed as the old ones.