I originally used the seal that came with the rebuild kit. It leaked. I got a seal from GM, and installed it, no leaks. The GM seal looked higher quality to me also. But if your seal from your rebuild kit does not leak, you have no problem I would say. It may have been a poor installation on my part to cause the leak, I do not know, but it looked ok after installation, just a significant leak of my penrite lube.
