REAR Differential YOKE Seal

Hi every one. I replaced the REAR differential cover gasket and fluid. The diff. housing has been really greasy on the outside, which made me suspect that the yoke seal was bad: It is bad..... When I removed the filling plug, I inserted my index finger, took it out.....no oil on it, so I used my pinky finger, and I had to stick it all the way in to get some oil stain on it. So I did all the proper cleaning of diff. cover and housing surface,,removed all the old oil, which was really dark and smelly,,, put a new gasket (it didn't have one, just silicone), with high temp. silicone on both sides of it and closed it. I added the new fluid, cleaned the diff. housing all around and drove for about 10 miles. I looked under and the yoke seal is leaking. I have the seal and nut, which I had from the JEEP dealer. My question to you guys is: Have you ever replaced the rear diff. yoke seal following the procedure and then had any major problem with the differential?. With all due respect to this forum, I want answers from people like me, who don't know every thing but try, learn and respect the rest of us. Thank you.