It’s extremely easy to wire an internal-regulator alternator without buying an aftermarket pigtail. The two wires from the generator to the old regulator go away (mine were melted anyway). The brown wire from the GEN light goes to terminal #1 on the 12SI or the “L” terminal on the CS130. Run a wire from terminal #2 on the SI or the “S” terminal on the CS to the junction block for sensing. Run a heavy gauge wire from the threaded BATT terminal to the junction block for the main charge wire. Finally, the CS family is sensitive to the ground path, so I always run a ground strap from the aft frame of the alternator to the block. That’s all that’s required.