i called a mechanic from MR Automotive in Redland bay,Qld. the guy was really helpful. suggested drilling a couple of holes into where the bolt is and spraying ROST OFF or INOX into them to soften the rust.
also as a last measure to cut it with a say if can get it apart enough but the alloy would need to be re-welded and ground.
Definitely a last resort.
I decided to drill a couple of holes into the bolt hole from the top, then sprayed copious amounts of INOX into them and will leave over night.
Next big job i will Definitely book the truck into MR Automotive. Thanks guys.

