Have changed both on four of my cars. Just changing the seal will not stop the leak. You will have to do the t-case seal (use a seal puller, it'll be out in a few minutes) and the yoke recall, as stated in the other thread. Did just t-case seal in 555/2k and within two days was leaking again. Did yoke recall and another new seal (because I wanted to make sure the seal wasn't leaking) and haven't leaked a drop from my t-case since.