This really sucks. I go to change the oil in my transmission-89 Amigo, 2WD, 4ZE1-and I find cracks radiating outwards through the threads in the filler hole. They don't appear to go all the way through to the inside, but it's so bad that some of the threads actually came out. Needless to say the plug can't be retightened. Is this a known issue with these castings? Could it be welded back up? I need suggestions BAD. I can't have this thing out of service.