I've included the best pics that I could get. [IMG][IMG][IMG]
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Hmmm. 50% larger is rather significant of a difference. And the bird appears to be well feathered too, which males usually bulk up faster and feather out slower then the pullets.
Check the bottom of chicks feet. It may be possible that you have a Jersey Giant that got mixed into your order. They look pretty much the same, with the only difference being foot color. Jersey Giants will have yellow on the underside of their feet, and Australorps will have a pinkish white sole.