i had a simular problem on a third member flange. it had a small almost unnoticable groove in it where the old seal rode. i sanded it down a little to smooth it out, but it still leaked. so i thought i had damaged the seal when installing, and replaced it. once again it leaked, this time i pulled it apart and decided to put a speedy sleave on the flange, it was about $30 at napa, and it fixed the problem. that small grove caused it all along. the other possible cause for your leak could be the problem i am experencing now, my rear output bearing on the t-case hase about a 1/4" play in it, causing it to leak. im pretty sure this isnt your problem cause you mentioned nothing about bad driveline vibes. hope this helps. Kory
