I'm guessing you're talking about some custom game. In that case it's probably not a default unit in the editor, you have to create it yourself. It might also use imported models that are not in the editor.
I do know that there is no "slugalisk" in the editor. At least I'm very sure of it.
Do you think it would help if I posted the pictures of the units to help me find where they got it or do I have ge tin contact with that map maker? Because between you and me, I doupt the units are from amateurs, they look professionally done.
Post some pictures and we can determine if it's custom models or not. If it's custom models, I guess you'll have to ask the creator of Desert Strike.
Viking Bay is a doodad model that can be found within the New Folsom group of variables.