I have a two wheel drive, 1999 F 150, 4.2 L V-6 and I noticed a spot of oil on the differential cover Saturday. Looks like the gasket is failing and will have to be replaced. I been trying to check the oil level and can't get the plug out. I cleaned off the area with a wire brush and applied some penetrating oil but was unable to get it to turn. There isn't much room to work without a hoist and the 3/8 extension has slipped out a couple of times. I don't need to drive it this week and would really like to take care of it myself. Any suggestions would be appreciated.
Thanks,
Mike

 

You Probably tried this already, First spray with a good lube, like PB Blaster, WD 40 works but not as well. Then using your 3/8 drive give it gentle wacks with a hammer. This should loosen it up, Make sure your using a good name brand 3/8 drive, fits always better. Also replace your cover, its cheap insurance and you wont go thru what I did. Replaced gasket and cover had a small pin hole, had to do the whole job over. Good Luck. Scott

 

Thanks Scott, I have been using PB Blaster. I tried your suggestion but the extension keeps slipping out. The hole in the plug appears to be slightly elongated, maybe 3/8 by 7/16, and not very deep. I've probably made it worse but the metal isn't bright so it been that way for awhile.
Where did you get a new cover?
Mike