There were really only two shuttles shown during the Original Series - the Gallileo and the Gallileo II, though the Enterprise was supposed to have several more. Oddly enough, the Gallileo was lost in one episode, and then reappeared in a later one, while the Gallileo II, which assumingly replaced the earlier shuttlecraft, didn't show up till afterwards. The shuttlecraft design was supposed to be much sleeker, and more of a pod shape, but AMT didn't like it, and they were paying for it's construction so that they could make a model of it. Why else would they do an entire episode named after, and based around the shuttlecraft? :)
This site owned by Infinity LTD, © 2002.