It looks like any of the following D-R regulators will work:

Output Amperage:36-42
(Edit: The current regulator can be adjusted to work with the 25-amp generator on any of these. Jerry)

Application: Delco Generators

Buick 1955-62, Cadillac 1955-62, Chevrolet 1955-62 Equiped With Delco Generator

Reference Numbers: Delco 1118277, 1118337, 1118338, 1118389, 1118739, 1118740, 1118745, 1118885, 1118886, 1118887, 1118888, 1118889, 1118890, 1118929, 1118930, 1118948, 1118973, 1119004, 1119163, 1119266, 1119275, 1119600, 1119602, 1119609, 1119610, 1119623, 1119627, 1119629, 1119630, 1119633, 1119637, 1119638, 1119639, 1119640, 1119648, 1119654, 1119655, 1119660, 1119661, D619, D623, D625, D627

My mid-1950's Delco-Remy service bulletin book lists the #1118825 regulator as the standard replacement item for regular-duty 12 Volt generator regulators. I'd also reccomend using an original-equipment Delco regulator, not one of the repops from overseas!

Edit #2: There are literally dozens of NOS Delco-Remy regulators on ebay right now, with various applications listed. Any of them can be adjusted to match your 25-amp generator, so don't automatically reject one that lists a 35-42 amp rating if the price is right. It's a simple spring tension change on the coil behind the ARM wire. It will make no difference at all where the max voltage setting is concerned.
Jerry

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