1985 Chevy 10 custom deluxe pickup truck, removing gas tank

I am removing the fuel tank (20 gallon) and have removed the plastic shroud. When the 8 bolts that hold the two brackets ( about 6" wide heavy steel " U" shaped brackets surrounding 3 sides of the tank and located near each end of the tank that bolt to the inside of the frame)are removed can the brackets be removed or must the strap running between the brackets and the tank holding the tank in place be loosened at the same time. I would surely appreciate an answer as at