Differential Cover Help

[blackdemon007]

I purchased this differential cover a while back - had the shop put it on during gear install.
http://www.americanmuscle.com/frpp-88-diff-cover.html

Now I'm in the process of changing the gear oil.
Got everything drained out, but I cannot figure out how to remove the fill plug in this cover.
It is some large sized hex.
A T-50 torque bit is too small and a T-55 is too big.

Does anyone know what is supposed to fit in there, nothing I have around the house seems to fit?
I already tried to remove the factory fill plug, but ****ing blo-hio has the thing so rusted, it is not coming out .

 

[whiplash473]

Doesn't look like a torx, looks like an allen head to me. It might just be the damn screen on the school computer though.

 

[PinkieT]

Doesn't look like a torx, looks like an allen head to me. It might just be the damn screen on the school computer though.

What he said. Big allen head.

 

[blackdemon007]

Doesn't look like a torx, looks like an allen head to me. It might just be the damn screen on the school computer though.

I'm pretty sure you are right, I just threw the torx bit sizes in there for reference, since I had them here and neither one fit.

 

[lutter94]

what pics?

 

[Thomas_W]

I still use the factory fill plug on the driver side front of mine.