I own a 2003 Buick Lesabre and I decided to replace both CV axles because the boots were cracked and flinging grease all over the place and I also replaced both seals. The seals were not leaking but they looked a little worn so I figured I’d go ahead and replace them since they were easy to get to. So I finished the job and took my Lesabre for a spin and my passengers side cv axle didn’t align properly with the transmission apparently because I heard a grinding noise and my car haunted and wouldn’t move. I popped the hood and took a glance and noticed the passenger side cv axle had popped out of place and there was transmission fluid all over the pavement. I had it pushed home and I removed the brand new CV axle and had to throw it away because the splines on it were shredded to hell. I popped the old one back in temporarily and took my car for a test drive and it drove like nothing had happened 
. The next morning, I noticed a leak coming from the CV axle seal so I decided to replace it with a brand new seal and it still leaked. Replacing the axle seals was just a pain in my ass at this point so I decided to have a certified mechanic install the seal. After they installed it, it was still leaking. At this point, I still have the old CV axle installed but have had the seal replaced 3 times and it still has continued to leak. I was wondering if maybe something inside the transmission was damaged that’s causing it to leak or if just replacing the CV axle would stop the leak. Any suggestions on what the problems could be or soloutions on how to stop this leak?
Our Mazda Protoge developed a similar problem but in that case the seal was going out within a few hundred miles, only on the passenger side. While diagnosing a noise from the manual transmission the mechanic determined that we had a defective CV axle on that side and since both had been recently replaced they changed both under warranty and there were no leaks again.
The bore in the trans/axle where the seal is installed may have been damaged by the splines on the halfshaft when it became loose as it was rotating,
So now transmission fluid is leaking from the seal from the outside of the seal.
Tester
Whenever possible I used flanged seals in all applications to avoid problems like this. And a thin bead of RTV at the flange was a final effort to avoid failure.
But certainly the inner joint moving out on the splines possibly damaged the housing beyond re-use.