Posted by Ben on February 11, 04 at 11:05:14:
In Reply to: Stubborn rear axle fill plug, 1990 10 bolt rear axle posted by Foy on February 11, 04 at 06:13:15:
If it's really stuck and will only get more buggered up, consider replacing the cover with one that has a drain & fill plugs.
Would assume most speed shops would have them in stock and maybe in the $100 buck range.
Otherwise try this, as it's worked for me in past. Take 1/2" extension and grind the square down to fit tighter into the 3/8" plug. Even have to hammer it in. Then take impact wrench, making sure it's home'd in really good.