What rkent said, but I often find it difficult to loosen the upper nut on the mount in place. With the trans supported by a jack, remove the 4 bolts holding the crossmember to the body. Then remove the 2(?) bolts holding the mount bracket to the rear of the transmission and remove bracket, rubber mount and crossmember. Clean metal and replace the mount and reinstall, starting but not tightening the bolts to the trans. Often it takes some levering around to get the 4 bolts started the hold the crossmember in. Once those are started you can butch the trans around, tighten the bolts holding the bracket on the rear of the trans and then tighten down the 4 crossmember bolts.