[65catalina]

I'm having voltage problems on my 65 Catalina. I had a bad alternator and just replaced it, and also did a test on the new one per the shop manual and it is putting out 55 amps.

Problem is, when I run any accessories like headlights, my voltage goes below 12V. So I'm thinking is a bad regulator, right? Well I had one from my 69 and put that on, and it wouldn't charge at all, even with no accessories on. So I bought a new regulator and put that one on, with the exact same results as the one from the 69.

Is there any differences in regulators from 65? The 65 uses only 2 wires, one on F and one on term 3. The 69 had at least 3 if not 4 wires on the regulator and was original and had the 2 coils with the voltage adjustment inside it that did NOTHING on my 65. The regulator that was on my 65 only had 1 coil inside with NO adjustments. The new one was all solid state.
So I put the original one back on and it will charge and run the car fine as long as I am not driving at night. Any ideas what could be wrong?????