hey yall i just added myself to this awesome forum and looking forward to learning all i possibly can for my 50 1/2 ton 3 window.

im rebuilding my brake system but was wondering, how will i know if i need new brake shoes? is there an indicater located somewhere that i dont know about or a certain thickness that the shoes need to have on them? i want to do it all right the first time but not waste money on things not needed. any adice would be greatly appreciated
thanks all..........murdoc