Not sure on the life expectancy thing either ... my car is not a daily driver, and I pull it off insurance during the winter where it sits garaged and covered. So, my car is lucky to see 3000 miles a year. So, I have never thought about the life of it. Mine has maybe 1500-2000 miles on it and I've had it 2 years now.

Interesting question about getting yours back. I was told that you would, so I put a small indescrete mark on my diff when I pulled it, and I indeed get my actual diff. back.

For more information, go to the Group Buy thread and do a search on Retrofit. You should be able to find the group buy thread from about 2 years ago when a whole bunch of us on the board bought them.