Flickering or pulstating Headlights

coalman said
I have the old style regulator, I can't tell if both or just one is insulated. A funny thing in my hard copy shop manual it shows the ground brush on the back of the alternator. Thanks again
Click to expand...

Is it on the car? Try a mirror?

Roundback
upload_2019-9-26_19-7-29.png

Round back Isolated field ('starting in 1970)
upload_2019-9-26_19-10-0.png

Isolated field round back with one terminal grounded with jumper.
upload_2019-9-26_19-12-33.png


Sometimes earlier round backs are mutilated to convert them for use with two insulated brushes. See here
Round back alternator
All square backs have insulated brushes.