It's a GMC ½ ton 4x4 and has the trailer wiring and rear air. The alt is rpo K68 which is supposed to be 105 amp according to the manual. The terminals on the alt plug are labeled P L F S. The L term has the brown wire and the F term has the pink & black wire. The alt post has the large gauge wire to the bat and a smaller fusible link wire. With the SI alt the fusible link wire goes to the fuse block, so I assume this one does too. The pink/black wire has 12+ volts with the key in the run position and when I pulled the gage/idle fuse it had no voltage, so it must go to the splice with all the other pink/black wires from that fuse. Interestingly the brown wire has no voltage with the key in the run position even though the diagram for the ign switch shows it hot in run, I guess it goes somewhere different than the diagram shows. /forums/images/graemlins/confused.gif So much for the accuracy of the factory diagrams!