The larger alternators on the YM's with two mounting tabs, are generic automotive from the same era, 73 Datsun or similar. That and the matching regulator are cheap at Autozone. Just specifiy the non air-conditoner version for a perfect fit. The higher output A/C one is fatter and needs a different mounting.
But this pancake 'dynamo' with just one mounting tab is unique to small Japanese tractors and similar (maybe battery-start generator sets?). I doubt Autozone has them. Ebay is where I've seen the best prices for this and its regulator.
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Trivia: Datsun IS Nissan. Legend: Some other firm owned a trademark named Nissan in the US.
Per the legend Nissan was all ready to ship over their first cars when they discovered this.
Strategy meeting "What will we do? We need a new name in just a couple of days!" Somebody replied "That Soon?"
"That's it!!!" the CEO replied.
It's sort of like that. Nissan was a Japan manufacture of wartime WW2 military vehicles, aircraft, weapons and chemicals. Nissan Zaibatsu.
So, when Nissan had to export vehicles to North America, the knee jerk to Datsun was to prevent shame and US veterans from raising the alarm of a brutal enemy against our soldiers. You mention Nissan to any WW2 veteran that saw extensive action in the Pacific rim islands and they will spew out a bitter hatred on the subject.
It's so bad, that Nissan was brought to trial for war crimes, yet they barely escaped without being charged.
from a history snippet ---
Nissan was one of the largest players in the Japan war efforts.
Nissan Zaibatsu actually moved its main plant to Manchuko, the Japanese Army's puppet state in Manchuria. This was significant because the old Zaibatsu like Mitsubishi refused to participate in the venture that was supposed to create strategic depth for Japan.
Aikawa Yoshisuke, President of Nissan, was briefly arrested by the allies on suspicions of class-A war crimes. He wasn't charged, but the Zaibatsu itself was dissolved.
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Datsun was it's own company till Nissan acquired it later in 1934. The Yokohama assembly plant under Nissan started to make Datsuns in 1935.
From the Nissan website
Birth of Datsun and origin of the brand name
[SHORT STORY] Birth of Datsun and origin of the brand name | Nissan Heritage Collection
The company that created the DAT (or DAT Motor Vehicle), which is where the name "Datsun" came from, was Kwaishinsha Jidosha Kojo, founded in 1911 by M. Hashimoto. His dream was to make cars that were suited to Japan and, if possible, export them. In 1914, when he completed work on a small 2-cylinder 10-horsepower car, he borrowed the initial letters of the surnames of his three investors (K. Den, R. Aoyama, and M. Takeuchi) and gave the name "DAT" to his new car.
Later Kwaishinsha merged with the Jitsuyo Jidosha Co., Ltd. to form the Dat Jidosha Seizo Co. It went on to produce military vehicles, but in 1931 the company developed a new passenger car (500cc, 10ps), which embodied the DAT spirit. It was, however, more compact than the original DAT, so it was called DATSON - in the sense of "Son of DAT". In Japanese, though, son is the word for "loss" so instead it was changed to "SUN", which has brighter associations, when the car went on sale in March 1932.
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So now we all known the rest of the story. Good Day! -Paul Harvey