Decide if you want to put a stock one in or go aftermarket with a polyurethane or maybe even a sphericle bearing joint ($$$). The stock one has a rubber center bonded to a sleeve that is pressed into the trailing arm. If you want to replace with oem you need a press and/or the special tool that I mentioned before. The aftermarket one leaves the oem sleeve in the trailing arm but requires you remove all the rubber to put the new urethane bushing in. You will also be reusing the stock "bar" that runs through the middle of the original rubber piece. The best way I've found to remove the rubber stock portion to put a urethane bushing in, is to burn out the stock rubber and then use a wire wheel to remove the left over ash before pressing the new urethane bushing in.

Good Luck.