This diagram incorporates the original 1950 wiring diagram somewhat and mixes in alternator wiring. There are, of course, many more wires in the truck but these are the ones you are asking about. Don't know what all has been added or upgraded to your wiring or truck. You may want to add more fuses and/or use terminal blocks for some wiring. This assumes you have a Delco 10si alternator and want to wire as "3 wire" configuration. No horn relay used on 1950. Can't think of anything from a 57 that won't "work" but advise what 57 parts you are using. This is the basic hook-up shown for reference. Use your magnify feature to read.
A wiring diagram is not meant to show a person exactly how each wire is attached. Sometimes there are too many wires on a terminal or it is better for routing to do this or that. You can splice, use a terminal block or a terminal on a component to join wires electrically. However it is important to accomplish the exact circuits per the diagram. Be sure you get the same circuit flow as the diagram. Wire sizes are determined per load.
To exclude a "run on" condition reported by some, if you are using the original ignition switch, advise how many terminals it has and then I will suggest some wiring....describe whatever ignition switch you have. It's good you are asking questions if not sure about wiring. Don't try to figure out how to use or incorporate old wiring circuits. You can snip both ends off of something and use the actual wire if it's in good condition. Some wires are just relocated simply. Colors do not matter. Nothing is hard to trace on a good old AD truck.
You need to look at the tech tip section, under "12V conversion but with alternator" and you will see the basics we are discussing.. Read that, it's a good overview of what all you need to do.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
