Directly above the fill hole there is a notch to hang the bag. It hangs in my Granite Gear AC60 just fine. If you click on the photo you can make it out. I'll upload a personal photo with a closer view in a moment.
No, if you are referring to the backside relative to the stock picture, there is not a hook on THAT backside. However, it there IS a hook on the front, just above the twisting lid/cap. You can see it in the stock picture.
As stated by the other people that answered, no. There is a hook above the filler cap or some packs grab the ring around the filler.. There is a almost handle under the filler that hooks onto the lip of some packs and hold it up.