The GM alternator conversion has been a great update for me! The 4 AWG wire directly to the battery really helps when charging under load while using the winch, lights and so on. I've melted the leads to the factory alternator before which may or may not charge the battery fully after 15 minutes of run time. This is the alternator mount that I used that bolted right up with very minimal grinding on the bottom mount.
Alternator from a 1995/96 Caddy Fleetweed Broughnom is what I started with. Thats a CS144 case, with the 12 and 6 mounting locations. If your current pulley won't line up on the new alternator, order a power master 111 dual belt pulley to help alignment. I believe I went to Orileys for the alternator. They sell the pigtail there as well. That makes it very easy to wire up.
You need a 4 AWG wire with ring terminals to go from the positive post of the alternator to the positive post of the battery. There is a plug with four wires, starting with the big wire (it has the larger of the four pins) they are:
S - connect this right to the "+" stud on the alternator with a ring terminal (big wire)
F - Not needed
L - Connect to 12V key on source at the fuse panel
P - Not used
The fuse panel has blade terminals on the back of it to hook up the 12v key on source. DO NOT USE THE AMP GAUGE, it may melt or catch fire, you'll have to pull out the cluster, disconnect the amp gauge and wire the two amp gauge wires together to complete the circuit. Then you'll need to disconnect the factory external regulator. That's it! Two wires with the third being the 4AWG to the battery. Very easy set up.
Some may say you need to wire in a 12v light to the 12v key on wire but you don't need it. Some threads may mention to wire up an alternator light, that's unnecessary too. If anything, wire up a digital volt gauge or buy a volt gauge that you can plug into the cig lighter if you ever have any questions as to weather the the vehicle is charging.