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No voltage, but the battery isolator prevents back voltage from the batteries. The output side of the isolator has voltage from both batteries.

[Tf175]

Mine is different , battery voltage present unless switch in engine bay is off . Does the small red wire have power?
My original Leece Neville was model # 3425 J .
The man I spoke with at Prestolite was Marion Jett .
That was five years ago .

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The small red wire is powered when the key is on.

[Tf175]

I found a reman 75 Amp Leece Neville online, Roberts and Son . The photo clearly shows the left terminal as a ground terminal . I stand corrected !

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Went back to the alternator shop and showed the tech a picture of how i had the alternator wired. He said it was correct also. His thought was to bring it in again for testing. I believe I will pull it again and let him test again. perhaps before i do that i will run a jumper from the negative terminal to the frame again. Pain in the butt. For grins i will start the engine without the alternator in place and verify that the output shaft turns.

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Thanks to all for the help. I finally sorted out the alternator. I removed it for the 3rd time and did my own bench test. It worked! Turns out it has to have battery voltage on the alternator + terminal as well as the ignition post. The battery isolator diode was preventing that. A simple jumper and it puts out 14.1 volts. Interesting that once it starts putting out voltage you can remove the jumper and it continues to charge. If you turn it off it needs the jumper to start again. Apparently once excited it doesn't need the jumper.

[Richard]

Thank you for posting the valuable info on the fix!

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It works again! Turns out that in addition to the ignition wire this alternator needs a direct battery connection. While it was connected to the battery isolator, (essentially a diodes) there is no voltage on the input terminal back from the battery. A simple jumper to the alternator + terminal provides the excitement voltage and voila it cranks out 14 volts!