My clutch is starting to slip under boost so I am going to have a shop replace it. I was thinking since I am going to have it apart I might as well pull the transfer case and get it rebuilt. It has 147k miles on it and it doesn't whine badly except when I am at 58-60 mph it whines really loud. Other than that it isn't super loud. I know the 03 evo 8 transfer cases are the weakest of them all and I plan to make a little under ~400whp/380wtq as my final goal.
After a lot of research I realized that finding all the parts to rebuild it is impossible because of discontinued parts. I really don't want to pull it and send it to shep,tre,jacks etc. because of the downtime and the cost to ship it. (I also wanted to buy a mistubshi lsd off of ebay from jacks to throw in there). So I need help deciding what to do. Should i just say "if it ain't broke don't fix it" or play it safe and have it rebuilt for peace of mind and added strength?
Is there a place that sells a rebuild kit for the non acd transfer cases that I have not found?
Any advice helps.

 

The weak part of the Evo 8 xfer case is the spider gears in the open front diff. You can certainly swap out the diff on your own. If it's whining a bunch though a rebuild might be in order.