rounded off driveshaft bolt help

[Crewy]

Well i have been taking my gearbox out over the last few days little bit at a time.

I have took the passenger side driveshaft off and today I went to take the drivers side one off and realised the previous owner has rounded one of the bolt that connect the drive shaft to the gearbox.

Does anyone have any idea how i can get this out, the main problem is space that aint alot of space to move around in so drill is out of the question.

Do you think if i araldite glue an old allen key or something in the hole be enough to get the bolt loosened?