Have any of you ever changed the U-Joints on your 4x4 systems before? One of them is rattling quite badly when it's engaged and I'd like to have it fixed prior to the weather going snowy and I may need the 4x4.

they aren't replaceable by design, but you can replace them.

 

rockford makes ujoints specifically for Subaru applications.  you can look them up for the part number or find it on this forum from previous posts, etc.  they're roughly $30 each.

 

requires some metal work - cutting out the old joint and properly fitting the new one. 

either do it yourself or have a machine shop/driveline shop do it for you.

Its no fun doing it, but once you've got the old ones out, they are much easier to service and replace if you ever have to again.

 

The factory joints are "staked" in, the new rockford joints have inner clips.

PDQ 1-0027 center joint.  Got them on ebay for about $20 apiece shipped.