The off-road crowd have been doing it for years.
You will also get a much better axle bearing set-up. No more using the axle shaft for a bearing race. The 9" bearings are pressed onto the axles and have their own races. That is why you need new axles.
You will need to cut off the axle flange on your 8.8 and fit and weld a 9" axle flange in it's place.
I will ask a buddy of mine, he races a Ranger in SCORE events, his 8.8 has 9" axles. Or try giving Currie a call, they may be able to help.
http://www.currieenterprises.com
I personally went to a complete Currie 9" diff/housing, no more 8.8