Charging System Upgrades
The biggest problem that an IH Scout has is with the stock charging system. First off the factory bulkhead connector is prone to failure, especially the early style. They are hardly heavy enough for the stock 37 or 63-amp alternator, let alone additional accessories. Most of the time if you add something like driving lights for example, this will overload the connector melting the amp gauge feed wires that pass through the bulk head connector. Most people just run new wires and bypass the connector. This is fine if the connector is already bad. Even if the connector is not bad you should run a new feed wire from the alternator directly to the positive battery post. This will bypass the factory amp gauge relieving it the load of charging the battery. The alternator will directly charge the battery through the added wire, not the factory amp gauge. The amp gauge will still show the discharge of the factory electrical system, just not the charging rate. You can add a voltage gauge if you want to monitor the system voltage witch will give you an indication of the charging rate. You can also just bypass the amp gauge by moving all the wires to one post but without adding a wire from the alt output to the battery you can still damage the bulkhead connector.
Any add-ons such as off-road lights, driving lights, or fog lights should be run directly from the battery via relays switching the main power to them. A stereo amp should be run directly off the battery post, positive, and ground both. I added an aftermarket fuse block for power to the switches that feed the relays and used a feed wire off the ignition switch to power the fuse block. Since most relays draw very little power this works perfectly and doesn't over load the ignition switch. You should add up the total current draw for the number of relays that you are using to be sure that you don't exceed about 10 amps total. Any more than that and you should use a relay to provide power to the add on fuse block.
I also upgraded the stock battery cable sizes. The factory cable is just too small to carry enough current to correctly feed the starter motor. The factory battery cable is 4 gauge and my replacement/upgrade is 2 gauge. The cables going to a winch will of course have to be as large as possible from the battery to the winch motor.
In addition to good power cables, grounds need to be good also. Besides the battery to block cable you should have a ground from the block to the firewall at the very least. I also have grounds running from the block to the frame and one from the battery to the front core support. I also have the stereo amp grounded directly to the battery. This will stop and feed back from the alt coming through your speakers. It will also stop your lights from flashing with the beat of the music while you are "cranking" on the stereo system.
Also remember to use rubber grommets in the firewall were the wires pass through if you have to bypass the factory bulkhead connector.
The next thing I did to improve my charging system was to upgrade to a higher output alternator. I replaced the stock alternator with a 90-amp 12SI Delco unit. This is a bolt on swap for any Scout with a gas engine. The only thing you might have to change is the location of the regulator plug. This change is easy to do with few tools. Just pull the alternator apart, then as you reinstall the brushes install a tooth pick in the brush holder to hold the brushes in place when you reassemble the two half's. Look at you old alternator for the correct location of the plug. I also replaced the stock two-grove pulley with a GM two-grove pulley, part number, #1852856. This is for an S10 truck. This pulley should be the first upgrade to any Scout regardless of what alternator used as it is smaller than the stock one and will spin the alternator faster eliminating the dim light problems at idle. Make sure you bypass the dash amp gauge described in the link below after installing this or you will destroy the amp gauge. You can also install a CS130 alt from a later model GM car or truck. The wiring is similar but the plug is different. I then upgraded to a 150 amp CS144 series alternator. Follow the link below for details.
Another modification that is popular is a remote starter solenoid. This will cure hot start problems for those of you in high heat areas. Follow the links below for wiring modifications.
Modifications To The Factory System