Actually, USS Amberjack is a Tench Class submarine. It is quite similar to the Gato/Balao subs and gives a good example to show the different phases of guppyization which happened to many WWII submarines. The word "guppyization" has it's origin by a modernization program called "Greater Underwater ProPulsion" shortened to GUPP. The first two pictures show the Amberjack in her original shape.

The next to photographs show the Amberjack in the socalled "Early Guppy II" shape. Taking a closer look you can see the overhang at the top of the sail which is the bulge at the top for the radar antenna.

Here she is in her final configuration, with the high "North Atlantic" sail. The upper rudder, visible here and in some of the other pictures, was installed about the same time she was first guppyized. Amberjack was sold to the Brazilian Navy in October 1973.

Photo source: Navy Photo Archives

Find out more about the Guppyization on Subnet.com or directly at their pages
of the USS Amberjack, the USS Quillback, the USS CLAMAGORE or some others.