I know you want to remove the plug and I realize the manual says to but in my opinion the risk of getting metal shavings in the housing is not worth the reward of having it vent while you fill it. You could fill the axle up, drive around some then let it sit overnight, check fluid level, correct as needed. In a couple days check it again and add if needed. Just my 2 cents. Also, if I was determined to remove it I would put a 3/8 nut over whats left and reach down in the nut with a mig welder and weld the nut to the plug. between the heat and weld it will probably turn right out.
thank
thank you, i'll grab an Easy Out
my concern with drilling through is that if you look at the parts diagram (or if you look down into the axle housing when you have the vent plug out as I did on the other side) you see that there is a major piece of your axle's gearing right under this tiny screw that is only about 6mm long. if you drill through, you drill into that expensive drivetrain part. then maybe you need to rebuild the axle