An attex is not an argo. And I agree I have never heard of a 6v attex or any other amphib actually. Why do you think it is 6v? What motor is in it? Maybe someone swapped another motor in it? Maybe some pictures will help.
The voltage is made by the alternator (AC charging coil) , which makes AC. The rectifier converts the AC into DC. The regulator stabilizes the voltage so it doesn't go up and down.
There are 2 main things that would make an engine 6V or 12V. The starter motor, and the alternator. They will both be the same voltage. The rest of the electrical system must be that voltage as well. The recifier can probably take either 6 or 12V. The regulator would need to be voltage specific, as would any other load like lights, motors, and so on.
I'm out.
Yes I did put Argo instead of attex sorry about that I put a voltage meter on the power wire,coming off the engine and its reading 6 volts no starter it has a pull start therfor no battery its a 1972
Not being a jerk,but,are you sure your meter is set to the correct range AND is working properly? I would go to a source with a known value and measure that to confirm operation of my equipment. Industrial electrician here,seen a lot over my days. Any time I measured zero on my meter I would go to a known source and have it show me 480 etc so I was sure zero voltage was zero voltage and not just a defective meter.