Module C4 is for Star Fleet Battles, and it introduced new races to the game, but they are computer-simulated races, whose physical appearences and cultures are not even explained in the slightest. Some make use of weird movement and new systems, some are based on types of real-world vehicles, and all are "Take-It-Or-Leave-It" types of vessels not a part of the "Real" Universe.
The most popular of these is the Frax, who use ships based on 20th Century Naval Vessels, and some of these, like the Qari, are based on real-world Nations, which is considered Satanic on here, and censored heavily, because no one must no that Nationalities exist, even though some people here write of the Cardassian Occupation and no one Bats an Eyelid.
Whatever.
These nacelles displayed are intentionally TMP-Era 1X Nacelles, making for some fairly advanced, but still Kirk-Era Vessels.