I have a brand new Wilderness Pack Specialties "Handi-Pak", custom made with a pouch on the outside to hold a water bladder. Also have a brand new gen IV molle frame to go with it. No shoulder straps or hip belt included. $30 TYD.
WPS has a picture of the handi-pak up on their website
--note that it's the cloth/strap part on the back side of the pack frame. Mine, as noted above, also has an extra full length pouch on the outside for holding a water bladder.