Yikes... How old is the truck? A pair of channel locks or the correct sized end-wrench should do the job just fine. It could've possibly been a metric sized screw (for lack of a better word) and you could've been using SAE wrenches; or even the other way around. The big deal now is getting them out without further damaging the screws. Relieving the pressure off the brakes by disconnecting the brake line may help to get the screw out. Other than that, just make sure you have a good grip on it if you're using vice-grips or channel locks.