65amp wiring/trouble shooting

Thank you very much! This helped me alot man. But there now is a new question. My '74 actually came with a rear window defrost option, so this makes it even more difficult.
The diagram is more difficult but you can spot whether it has the optional setup pretty easily.
On the firewall you should see the grommet with two heavy wires coming through.
Post some photos and we can point it out if its there. We might see other things too

ell uhm the thing is I was driving down the highway at around 75mph (speed limit here in Switzerland) when it started to smell badly but it stopped when I pulled over, shut off the engine and started again. It also never smoked again. At home, the battery was overcharged with more than 18V, but the ammeter never went into an extreme (how I remember)
H'm post some photos of the engine bay firewall, battery and alternator and voltage regulator.

If the ammeter was pointed 1/2 way toward charging, that would be 20 amps.
That's not a problem for a few minutes, but if it continues for long time at 20 or even 10 amps, that indicates a problem.
When its doing that, put a voltmeter across the battery, and if you see 18 Volts you like you did, then problem is probably the regulator.
Confirm its the regulator by measure votlage to ground by probing the connectors closest to the regulator's 'sensing' wire.
On '74 these would be the blue wire feeding the alternator's rotor and connector at the ignition ballast with blue wires.

I can post photos later.