Lots of reading on old Delco generators and regulators here: http://www.navioneer.org/riprelay/The%20Navion%20Files/navion.htm

Looks like your generator is 45 amps.

Regulators for positive ground vehicles are different than regulators for negative ground vehicles. Voltage and polarity should be stamped on the base.
see page 8 of this document: http://www.navioneer.org/riprelay/The%20Navion%20Files/Delco_Remy_Generator_Regulators.pdf

Gord 🇨🇦
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1954 1/2 ton 235 4 speed