My local (independent) shop here helicoiled my '05 EGC about 5 years ago and I haven't had a problem since. 2005s, the drain IS on the outter primary!
I did find a different plug with a magnet and used an O ring. I know it probably shouldn't have worked but it is holding steady. Just have to be REAL careful when loosening and re-tightening that drain plug for fluid changes.

 

That is another simple option for the OP - and probably what someone before you did when they stripped the original drain threads.

 

You could be right. Tapping it for a 3/8 NPT would be a good fit. You may just be able to do it 1/4NPT and would not even have to drill it. Would work if you could find a long pipe plug with an allen wrench hole. That is what is in mine.

 

I may just pick up a "new" outer cover and go with that. If I can get one for short $$, it would save a lot of headaches.