Outer Limits 4x4 Board

ok changing my front seal on my tb42 auto patrol have a big ass breaker bar but cnt wrk out how to lock up the engine to undo the balencer bolt any1 gt any experience on this? Wish it was a manual at times like this.

All sorted nd done

work out what way the engine is going to turn when you hit the key and jam your bar up against the chassis and hit the key it should crack the nut or try get a good rattle gun in there