Hello fellow motorheads. I have put 91 350 into 81 chevy truck. Obivously a wiring issue. The 91 alternator has a wire coming out of (L) on alternator plug. The other wire ports are open with no wires on P,F,and S. I had it tested and it passed. Anyone know how to make it charge? It put out 105 amps on bench tester but had 4 wires in plug from machine. ANY INFO APPRECIATED. Thanks guys and light em up when you can!