The Trump 1:144 scale Fleet Sub currently comes in just one flavor - Gato, as launched. They are planning another version for release next year as the 1944 Gato, with cut-down conning tower. Personally, I think it is a better size for displaying several versions. At 4.5 feet the Revell is just too big.
The Trump kit as the early full conning tower with streamlined periscope fairings. The model has the early limber hole pattern and Trump messed up by putting anchor wells on either side of the bow. The kit comes with an inner hull liner -- with some rudimentary bulkheads. Whether that is a hint of things to come? But whrn the hull is cemeted together there isn't any reason. I cemented the inner tube together without the bulkheads and glued it in the hull halves for some inner strength.
The deck gun is totally bogus. The water cooled 50 cliber gun isn't too bad. The stern tube doors are molded open and closing them would involve some rework. The decks are molded with some pretty good planking. The conning tower is a bit spartan.
It is heads and shoulders over the Classic Warships 1:350 scale as-launched Gato. That one comes without any limber holes or brass. It is also waterline only.
It is also difficult to compare with the Toms Balao. That us a late-war full cut-down conning tower. The Toms Balao has depressions for a full limber hole pattern and all the petite details, rails, props, etc are etched. It is difficult too to compare with the Nautilus Models (now ISW) Nautilus. That has a unique way of forming the conning tower base limber holes. Again brass for the smaller details.
Nautilus Models has come out with some aftermarket conning towers and guns.
http://nautilusmodels.com/Gato/144Gato.htm
They offer the Haddo with the first cut-down, the Gurnard with the second cutdown and the Thresher, which was a member of the previous Tambor class, but externally quite similar. It has the second cutdown plus some deck sponsons and mufflers.
White Ensign Models will be coming out with some 1:144 scale deck guns as will Iron Bottom Sound.
White Ensign will also be coming out with some PE for the kit (date & price are TBD). Tom Harrison has declined to do anything for the early Gato. He told me that he was going to hold off until the later version comes out. Nautilus Models is also doing some PE, James Corley has said that he is re-scaling his PE that he had for his Revell Lionfish towers.