Resurrecting an old thread because I have the same t-case leak, but it's not the front seal (which I've replace at least twice). The problem is that the gear lube leaks from around the soft plug in the u-joint end of the slip yoke. It drips off the yoke/u-joint, not from the seal dust cover which is to the rear of the u-joint. Ten months ago I packed heavy grease into that end of the yoke. It didn't leak until a week ago.
So without replacing the soft plug, what can be used to pack or coat and seal the plug from the inside to stop the leak and still unsure proper slip yoke operation?