that rear seal is a PIA I did my drivers side a while ago and it seems to be okay, i don't smell diff fluid any more...it wasn't to the point that it leaked on the rims yet. but I did go through about 3 seals till i got one that sat right in the bore...I had a hard time getting it to go in even on all sides...this was also leaving them in the freezer for 1/2hr to 45 mins i guess i just suck at it. After that I did the extended breather mod.