Replacement Tugs is an episode.
Big Mac and Warrior is going to work for the Jenkins Fleet for some days and Zebedee and Zak is there replacements. Zebedee does Big Mac's work while Zak does Warrior's garbage work, they like working for Captain Star and Ten Cents ask if they want to join the Star Fleet however, they say no. Meanwhile, Zorran, Zip and Zug is doing Zebedee and Zak's work as well as their own.
Later, Zebedee and Zak is nice to the Star tugs which makes Captain Zero angry and he kicks them out of the Z-Stacks. Zebedee and Zak no longer has a fleet now they try to find one and Captain Star needs two tugs as replacements. Ten Cents and Sunshine meet Zebedee and Zak and the former Z-Stacks reveals that they want to be part of the Star Fleet then they tell Captain Star and he buys Zebedee and Zak, he renames them Sebedee and Sak which they like and they get a Star tug livery.
Zip and Zug become Captain Zero's 2 and 3 tugs and he buys Burke and Blair and they become his 4 and 5 tugs. Sebedee and Sak now live a good life and they are happy that Captain Star bought them.