Interesting - if you check the model numbers on SOs support site the 53715 is listed as a Android 2.3 device whilst 54585 is an Android 4.0.
I'd be wary of a 53715 claiming to be a 4.0 - have a read of this review :
http://www.amazon.co.uk/product-reviews ... TIOJDV3R1A which mentions someone ordering a 4.0 and the "paperwork" showing a 2.3.
BobC