Finally gave up and got a one wire alternator

[KFunk740]

 

There she is on my J13, nice constant 14V.  Driven it maybe a couple hundred miles.  Just search for Datsun one wire alternator and this popped up on Amazon and looked close enough:

https://www.amazon.com/Electrical-ADR0152-Self-Excited-90-01-3125S-70-01-7127SE/dp/B0081S9C16?fbclid=IwAR0OHMC6cHrNJ-FwB3f21Waqmd-za98edIext5njvoOatHYmAywhoBtjBXc

 

Biggest concern was space between the block and the battery tray, and couldn't find dimensions online.  I went ahead and gave it a shot, and it fit fine with no modification.  It fit right in the bracket that was on my truck (no idea if that's stock, but it has fit other Datsun alts).  I tried to make external VRs work for 10 years, and mechanical was certainly better than electronic external, but the mess of wires was a pain and the voltage was all over the place and went high too much for my taste.  I ripped out all the extra wires and VR and put them in my workshop.

Edited November 3, 2020 by KFunk740

[datzenmike]

I think the stock J13 alternator was like 28 amp so this has got to be at least double this. I noticed with a higher output the heater blows better when idling, with the headlamps on and the headlights don't flick with the turn signal.

[KFunk740]

It says its 63 amp.  The headlights may be better, not sure.  They've never been great, and I've never bothered to figure out how to aim them properly, hah.

My heater switch/blower has always been a little goofy too, no real improvement there, but again probably not due to lack of power.

[datzenmike]

The lack is usually when they are all on and working, lights, heater, wiper. 

[KFunk740]

It's been a couple weeks, but DB Electrical finally sent me the exterior dimensions I e-mailed about, hah.