The GOP wouldn’t have the balls to use them, even if they existed... 527s, on the other hand...
It's a lousy hand the GOP is always dealing with from the get-go no matter how strong/conservative a nominee is or is not when they have to counter emotional conclusions from the Dems, the media, the teachers, Hollywood etc.
The Dems can always have more open association with some of their 527's but the media will not demand that the Dem nominee needs to squelch the 527's supporting him/her while of course McCain will told he has to.