Thought I was very careful to get them this time, silicone worked on that I'll try a bead on this & see if it helps, my vac gauge is not steady.
The first thing you do when hunting down a vacuum leak is double-check every bolt on the induction setup. Are all the manifold bolts tight, and did you do them in the correct sequence? Are the carburetor fasteners tight enough?
Silicone is not fuel-resistant, so it's not even suitable as a temporary repair. It should never be used on the intake-to-head junction or carb gaskets. It will not last even a little while, regardless of color.
Also, I believe we covered this a long time ago, but due to the age of, and God-knows-what's been done to, these engine parts, the intake-manifold front & rear end seals seem to create more problems than they solve and should
always be left out. Silicone only, with the intake installed after the silicone has "skinned over" but not fully cured.
Now that I changed that bulb I'll try the blinkers again with key on run, but not started?
They should work whether the engine's running or not, as long as the key's in the "RUN" position. I do not believe they work with the key in the "ACC" position (backward from where the key comes out) but it's been so long since I tried that, I honestly can't remember. The hazards should work whenever the switch is pulled, regardless of key position.
If you notice I'm doing everything & anything to postpone the electric & tuning hunts!
OK, stupid question time: Have you actually tried twisting the panel dimmer on the dash far enough to turn the dome light on? Just on the other side of the dome light detent is full panel brightness.
Next stupid question: Back during the interlock debacle, you pulled the switch panel to check continuity for the windshield washer wire. Did some wires come loose or not get reconnected when you did that?
Stupid question #3: Everything looks right with, and is fully connected at the turn-signal connector on the steering column, right? No huge burn marks or terminals pushed back far enough to not connect?
The tail lights, side markers and instrument cluster lights are on the same circuit. When that fuse blows, you lose everything but the turn signals, brake and headlamps. I know you checked the fuse, but it's one circuit that runs all of 'em so it's likely something simple. If you still have a printout of the bulkhead disconnect, or a '74 FSM, it's cavity 10. It should be the only black wire with a yellow tracer on the center connector on the engine-bay side. Black with a tan tracer is right below it; that wire's the RH turn signal circuit. The instrument cluster lights are fed by (surprise!) a black wire with a yellow tracer at the panel dimmer switch. The panel dimmer operates all the lights on the dash, like the one above the heater controls, the one in the factory radio, and even the shift-indicator light in the console (or on the column on cars so shifted).
Unfortunately, the novel design of the E-body headlamp and panel-dimmer switches does not make it easy to simply try different ones since they're specific to these cars. The headlight switch for vritually every other Mopar is still available new, and it's cheap to boot. Chrysler used it well into the 2000s. E-body switches, on the other hand, are expensive used and the price becomes truly unholy when you shop NOS.
The orange and red "triple taps" that you found are indeed accessory plugs (for options you may not have). The red one is 12V+, key on I believe, and the orange one is connected to the dash lighting. The orange one should
only have 12V when the lights are on, and its voltage changes as you rotate the panel dimmer. That orange tap is where I have the lights for my aftermarket gauges and tachometer connected, so they match the brightness of the cluster.
The key-release lever on the column has no electrical function whatsoever. Long story, but it's literally Chrysler's workaround to avoid completely redesigning the floor-shift steering column used in 1970. On the '70 models, the key couldn't be removed unless automatic transmissions were in Park or manuals were in reverse. Every transmission option (except column shifters) literally had complex linkage running from the transmission to the column just to operate a key-release mechanism. In '71, they did away with that and installed the lever behind the keyswitch. It operates the same locking pawl as the intricate, expensive 1970-only trans-operated arrangement.
There are only a few possibilities here: Something's not connected, a fuse is blown (which you checked), you've got a bad switch (headlamp or panel dimmer, since the former feeds the latter) or there's a broken wire somewhere.