Outer Limits 4x4 Board

I have a 1989 rn105r 5 spd I assume its a g52 gearbox and I tried replacing the oil this afternoon however some nob has burred out the hex filler plug making it impossible to loosen so I was going to try fill it from the bolt rouglhy 10cm to the right of it but I thought I would ask someone here first whether that is the best option to take or maybe just remove the gear stick and pour it down there, I dont know much about this so any help would be appreciated, also does any one know how much oil the gear box takes? cheers

Those alloy plugs burr very easily especially the ones that take allen keys to remove. I did it to nearly every plug under my prado when I first got it In most cases I have taken to them with a file and got a smaller spanner over them or got out the dremel and given them new edges. In extreme cases you can take a cold chisel to them. I've now replaced nearly all my plugs with steel plugs. Filling via the gear stick is
not a bad idea, I'd do that over removing another bolt somewhere on the box.
BTW- if you want to find out oil amounts any of the major oil companies have websites that will tell ya.