Hy Mark Miller, there are many possible reasons for slow cranking, the starters electrical circuit is only one of them. That being said, it sounds like you have a good basic circuit. Are all your connections clean and tight, are your cables the proper size for the voltage you are working with, six volt cables are twice as large as the twelve volt ones you find in the auto parts stores. In addition to the ground from the battery to the transmission, there should be a large ground connection to the frame (chassis), and other smaller ground wires to the cab, and front fenders, and the box or bed or deck. You can't have too many ground wires, hope that helps.
