Of course after draining and replacing diff cover and gasket, I'm thinking, just take out the fill plug, pump in new gear oil and I'll be all done. Another perfect job. But.... one look at the plug and I can see some trouble. The plug is deformed and somewhat rounded out. So I grind down a 1/2'' adapter down to fit the square hole better but no dice, that plug is in to stay. I think I'm just making it tighter when I tap the new tool in.
So my question is, can I fill the diff by removing the speed sensor and pumping in the correct amount of fluid? Other than that I guess a diff cover with drain and fill plugs is the answer. Any ideas? Thanks from Utah.

 

You can but the drain plug is where you add & check the fluid level at. tapping the tool should had helped by jaring the threads on the plug.

I would get the plug out if possible. Spray it with Kroil or PB Blaster,also you may have to go with a long handle breaker bar or put a cheater pipe on what you have to give you more leverage or a impact if you have one.

 

If all else fails take a 3/8 extension grind the mail end off to get rid of th rounded end make sure ther is no debris in the plug and weld it to the plug this will give you a nice square hole and the heat from the weld will help loosen it then instal a new plug with teflon tape and not so tight.

 

They make a tool specifically for this issue. It's a square tool with all four corners cut to a blade formation. I've used one thousand's of times when I worked at an oil change shop. Never failed to remove a stripped plug. Check it out. Top right corner.
http://ctatools.com/catalogs/2012NewToolsSupplement.pdf

 

Differential plug extractor. Man I even like the sound of that. I'll be looking for one in the AM. What do you use of the other end for torque?

 

6 point socket, six point box end wrench, crescent wrench, etc.

 

So the guys at the auto parts store let me borrow their easy out set and sold me a new brass plug. After much effort I finally got that S.O.B. out. I didn't think it was going to come out but just when I was ready for a different plan it turned loose. Thanks to all for the advice.

 

this may sound funny but if you try to tighten it just a little bit ( just enough to feel it turn ) it will usually break loose with little effort. it's worth the try

 

That's what my Grandfather alway said, it works good on taper pipe fittings in intake manifolds too.