Larry, the best explanation for that is that most people really don't understand automotive wiring.They wind up with extra wiring that's not needed or makes a mess or is hard to trouble shoot if there is a problem sometime down the pike.
If like on your 460 the tractor isn't stock (alt conversion) there is no need to try to keep the wiring stock. You can make the harness simple and easy to trace.
You have to remember that residential electricians may not understand automotive wiring and the opposite is true too. I know guys who are pretty good mechanics but at a loss with electrical problems too.
You also have people who put conversion kits together that try to make a conversion as simple as possible without concern that maybe there is a better way to do it.
There is a guy on one of the forums here that got an electric ignition conversion for his tractor that included a 12 volt coil to replace the original 6 volt. The kit also included a ballast resistor to used ONLY if the 6 volt coil was used. The instructions were not real clear and he had to ask advice on it to find out that he needed to remove that resister from the circuit. Now I'm pretty sure that what happened is the supplier was selling a pre packaged 12 volt plus IE kit designed to use the 6 volt coil. As a customer convenience they were shipping the kit with the optional 12 volt coil without additional instructions. Most likely an oversite on the sellers part. Not a real big deal as long as one has something like this forum to fall back on or the seller has good customer support. I'm sure that some 12 volt conversions have had similar things done to make it easier on the installer.
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