It sounds like your refering to the torque converter seal. If so once you get the trans. out you just slide the torque converter out and the seal is right there in the front of the pump. You can use a seal remover to get the old one out or if your careful a large screwdriver and hammer will do. Just be careful not to knick the pump. Then if your lucky enough to own the proper seal driver drive it in with it or if you don't have the driver drive it in carefully with a large (approx. 1" diameter) pin. I use an old kingpin. Grease the torque converter shaft and install the torque converter and trans.