Unfortunately, McCain referred to them as the Republican Guard also.
Was that at the debates? I watched the debates and heard McCain refer to them as Revolutionary Guards. I don't recall him using Republican Guard in relationship to Iran. In fact, someone on the debate thread made a point to ask if Obama had just called them "Republican Guard, and there was at least one response to their question in the affirmative." My power went out about midnight that night, and I ended up having to wait until the next morning to go through the whole debate thread in detail because it was moving too fast to keep up with all the posts. I don't remember reading anything about McCain using that term.