Something is pulling juice and draining the battery overnight.
Never had this problem before. Eliminated the alternator, starter motor, solenoid
Starter cable, HEI ignition module, add on aftermarket tachometer and guages and their lights. No dash, door or trunk lights are stuck on. The trunk(hatch) pull down motor is not stuck on. Haven't checked its power relay.
Thought maybe the little light in the center console was staying on with the cover closed but thats not it.
On a volt meter it pulls about 9.5V and about 1000mA when checked between the negative battery cable and engine ground. Pulled ever fuse and checked the old computer wiring (EFI computer removed) There is no computer or electric fuel pump or under hood light. It is something that is not switched by the ignition key.

I'm stumped...

 

when pulling all the fuses in the fuse box, none of them cause the current to drop? if that is true, then it is somewhere that has been added on, not being powered through the fuse box that is drawing the power. I see you've checked out a large number of things already, but one of the fuses in the box must be drawing power, unless it's an add-on type current draw, since all the factory wiring goes through that box for power.

 

The positive battery cable goes to the starter solenoid but also goes to a junction block (B+). There are 3 or 4 red (power wires) that come off that junction block as well as the alternator + wire. The current drain is coming thru one of those wires on that junction block.
Could not disconnect these wires as the thing (junction block) is made of plastic and the screw stud just spins in it. But its not the alternator.

The only add-on electrics are a tach, two guages and the headlight doors are controled by a Power antenna switch (manual) The factory head light door control electronics died a long time ago. All are powered thru the fuse block.

I'm thinking hatch pull down circuitry. (relay, switch)
rear compartment hatch light switch or relay. head light switch, ignition switch (column) Seat belt buzzer circuit.??? Some computer, EFI Emmisions control relay thatI'm overlooking. All the emmisions stuff EFI and computer is all gone. origionaly a 2.8L V6 car with EFI.
But all the wiring is still there.