383, Ez wiring harness.
New dual field alternator. Replaced other thinking it was bad.
2 different new voltage regulators on hand, thought one was bad.
Top post of voltage regulator has a switched 12v, going to field post on alt.
Other post on voltage regulator runs to other field post.
Getting too much voltage, reading 16-17 volts.
Any thoughts?

poor grounds, primarily the VR to body, battery to body, alternator to engine, and finally engine to battery.

You're full fielded (or very close to it). do not run it like that for more than the 3 seconds it takes to take a qhich reading then shut it off & when you do have all bulbs/acc OFF cuz 12V devices ain't comfortable with it jacked that high. What Super cuda said, clean ALL ground paths then clean all positive paths if the ground path cleaning dont do it. Especially the bulkhead. You've replaced the alt & the reg & all that is left is the wiring UNLESS the battery is sulphated/toast & wont take a charge so the system ups the rate to try & make it charge. Tossing in a known good fully charged battery will quickly elim or confirm that then you can move on to the fun part of cleaning all connections! Holler how it turns out. EDIT '70 up system correct?

I've triple checked my grounds .
I replaced the alternator with another new one tonight.
I tried both regulators and still overcharging.
Could it be something with this brand wiring harness?

Yes.
Both terminals of the regulator DO NOT go to the alternator.

I had an over-charging situation on a truck. I replaced the VR with a parts store part and nothing improved. I then went to the dealer and bought a Mopar VR and never had a problem again.

Just another thing to consider.

Just to clarify: the blue ign1 switched 12V goes to the top nub terminal in the reg (with the triangle pointing up like a pyramid) and that blue wire T's & also goes to an alt field terminal and the other (green wire) goes directly (& only) from the side terminal in the reg to the other alt field terminal (& nothing else is connected to that green wire). If it is a pre '70 system with the "box" reg then the blue ign1 feed wire goes to the "ign" side of the reg and the green wire goes from the "fld" terminal on the other side of the box reg to either of the alt field terminals (& nowhere else) then you ground the other alt male field terminal to the alt case housing with a NAPA 725145 female brass terminal (might be 725147, the counterman will know) and a short wire and a small ring terminal under one of the mini bolt heads on one of the three small bolts that holds the alt case halves together

Yes, they do

the ign + / field wire turns the regulator off / on and makes power available for the field windings. It also serves as a "sense" line to tell the regulator how much current the battery / system needs to maintain the existing load

The other field connection applies a variable ground to the field windings which in turn controls the alternators out put.

So, based on the above you either have

1. A bad regulator
2. a bad ground at the regulator
3. A pinched field wire between the regulator and alternator
4. A bad alternator/ ground.
NOTE: if 1-3 do not apply, I suspect one of the field terminals is grounded to the case