I looked at a picture of your truck and there is a regulator on the firewall. Maybe it's not used anymore?

https://www.stovebolt.com/ubbthread...gs-from-the-netherlands.html#Post1431886

Some 10si alternators were converted to one wire alternators. The "DA" plug will be missing on these.

Perhaps you should post a picture of your alternator.

Gord 🇨🇦
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1954 1/2 ton 235 4 speed