Rear differential fill plug size?

[Infinitiguy19]

Does anyone know of a socket I can use to remove the rear differential fill plug? Its appears to be a pipe plug fastener and larger than a 1/2 inch, At least the fill plug is. The drain seems to be a 1/2 inch. The fill plug is not rounded but a two foot breaker bar wielded by a 300+ pound guy on a lift could not break it loose.

I do not feel comfortable with torch near so much oil under pressure (Active Q45).

I soaked it with whatever I could find in the shop and no luck! The drain plug is loose, Didn't drain diff yet. This is for a 1994 Q45 non vented diff cover.

[elwesso]

It appears you can get one of these..

http://ultimatetoolco.com/13mm

13mm square would be what you need..