Dual voltage electrical system

I have a recently added M715, but its been modded with several things that I am trying to decypher...and the previous owner was not the builder.
One is it has a 69 pontiac 400 V8 in it, and what looks like an alternator on it, but only one cable leaving it, with a vacant plug-in spot that has two terminals in it. I see the wiring diagram shows that , but in all of my by-gone days of muscle cars, mopar, the alternator had a multi-wire plug on it. My curiosity is further complicated by what seems to be a mid-point tap of the crossover cable connecting the two batteries. It also seems that the positive cable coming from the front battery only goes to the starter.
SO, here are my questions...in the dash are some newer Sunto gauges...is it possible the 2nd previous owner found a 24volt starter that fit that engine and rewired the motor and the cab electrical system to be 12 volts?
Thanks

Moved post to open discussion.

On a GM alternator, it's easy to convert to single-wire. Don't know about mopars. All you have to do is run a jumper wire from the charge terminal to the exciter terminal on the alternator itself. (not sure that's what it's called, I am in a hurry and typing fast).

Get a meter and measure the voltage from that starter lead to ground...I'd put my money in it being 12 volts. I am assuming you still have 2 batteries....are they maybe now in parallel, not series, giving 12v from both?

Sounds like they left the factory starter and converted the lighting system...

What alternator? 12 or 24 volt?
What ignition? military 24 volt or civilian 12 volt?

Tapping off one battery to run 12 volt and using both for 24 volt IS going to ruin batteries...either need to run a dual voltage system OR use a 24 to 12 volt converter...but dont tap off one for 12 and use both for 24 at the same time...

Quote:

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Originally Posted by brute4c

Sounds like they left the factory starter and converted the lighting system...

What alternator? 12 or 24 volt?
What ignition? military 24 volt or civilian 12 volt?

Tapping off one battery to run 12 volt and using both for 24 volt IS going to ruin batteries...either need to run a dual voltage system OR use a 24 to 12 volt converter...but dont tap off one for 12 and use both for 24 at the same time...

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" it has a 69 pontiac 400 V8 in it"

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Speed (reading) kills....

It is possible that a starter shop rewound the 12 volt starter to 24 volts if that is the voltage at the starter...
Going around the truck with a multimeter and seeing what voltage is where would be a good start...

Brute,

Simple question, and believe me... I am not a starter expert at all. Wouldn’t you want to check amp draw vs voltage? Since the system is 12 volts, you will get 12v (with a little dip) at the starter regardless of what the starter is wound for. But amps draw would show you if it is good/bad. A typical (no load) 12v starter should be 60-100 amps or so... a 24v starter would be double that on a 12v system since Volts = Amps x Resistance?

https://youtu.be/ABdgkHI8qSs