I am a bit puzzled, the Ammeter feed just supplies the current to whatever is causing the draw.

Yup... I have been through the 3 firewall connectors.....and isolated to that one lead... now I need to figure out where to go from here.....

Seems the issue is something that doesn't go back thru the firewall, so it's inside the pass compartment or maybe the trunk. Years ago I had a problem with my battery draining over night, Eventually, I found out that when I replaced the trunk lid weatherstripping it was now thick enough that the trunk light stayed on. No idea what kind of current draw that light pulled, doubt it was anywhere near what you are seeing, but pull the bulb and see.

I would have guessed it would be either the ammeter (P terminal) or the alternator terminal (J terminal) as they are connected to the battery directly. If you look at your wiring diagram, the alternator terminal leads to a splice in the wiring harness in the passenger compartment that feeds:

1) Ammeter
2) Ignition switch
3) Headlights
4) Fuse panel (always energized circuits)

It looks like it's one of them.

Am leaning towards the Ammeter since its original.. have pulled the headlight switch plug...not sure that is sufficient. Pulled individual fuses...but not all at once...will try that. Also disconnect the 2 large flat white connectors ( ignition switch and turn signals) Is there another connector..?

You can bypass the ammeter by disconnecting & tying or jumpering the two leads together. If the draw is gone the ammeter ( unlikely) or it's insulation for the posts is the problem. IF not, you'll know it's not the ammeter.
Just an FYI: Hopefully someone did not use rubber washers/ tubing for insulating the posts and rubber can be conductive keep us posted

Thanks! Have a show on Sunday so will attack on Monday. Will the rally dash instrument cluster come out easily? I installed the dash fully assembled...

Didn't someone recently discover a miswired harness from Year One?

I'll look after breakfast. What I can't get my arms around is the 5 amp current. At that current you are dissipating over 60 watts of power. Typically you would be burning something up. Are you absolutely sure you are reading that correctly? That it's not 5 ma?

Can I delete this post...?? First...I need to remember how to uses a meter correctly. Measure with the lead in the correct port...300ma port and not the Volt/Ohm port..the draw when measured from the neg battery terminal to the neg cable is 10.3 ma....OMG..... Sorry to waste everyone's time!!

Don't worry about it. Sometimes the learning path is not smooth. All that matters is that the concern has been resolved. I wouldn't worry about 10 ma.

Thanks....its probably the clock....which actually works... lol

You can unplug the clock to confirm that is the only draw. Several other things can stack up if you have anything in the car like an upgraded radio etc.glad you found the issue LOL

Another comment is: I have found disconnecting the battery when parking for extended periods will drastically prolong their life

I recently had to chase down a parasitic draw that turned out to be the alternator but along the way I had to deal with a faulty voltmeter too. How annoying that was because it was throwing me off until I borrowed another to find it was part of the issue.

Wish I could blame the meter..LOL

the main thing is you now have the issue solved !
just wait until the "cobwebs" start to invade your noggin, like me !

Whats sad is I was a electronic tech for 5 years....and a BSEE for 30........

Haha no biggie we all do something like this now and then just glad you solved it

LOL It sucks getting old AMHIK

Had one that drove me around the bend for a while. 57 T-bird, 10 or 15 ma draw as i recall. Car was bone stock. Checked thi s, checked that, scratched my a-- etc. After a few hoursone of the guys says disconnect the clock. I said why? It doesn't work. Another hour or so of the above. Finally disconnect the clock. POOF! draw is gone ? WT-O?
Being an old points style clock, the main spring had broken and consequently the points stayed closed and the motor that wound the spring was running continuously