GMC S15 Sierra Pick Up motor support

Hello

, I have a question, as the motor supports of this truck are removed, try to remove them in a common way like those of other pick up, and other cars, but do not yield, the screws loosen them, but they do not seem that they climb as normal that when loosening a screw, I tend to climb to thread, the bridge is completely closed, so I do not think it is a last screw with a nut, or if it is so bridge and then the truth I need to change them.

any help is grateful