Today I connected the wiring from the front to the rear of the car and tested the exterior lights. The car has a new wiring harness from front to rear with new switches, lights, outlets, bulbs, and flashers, and I believe all the ground wires are securely fastened.

The headlights burn, both low-beam and high-beam.
Without the key turned the LH turn signal works.
With the key turned both turn signals work.
The front parking lights and rear lights don't burn with or without the key.
The emergency flasher turns on all four corners, but they don't flash, and the RH bulbs don't burn as bright as the LH.

Does this sound like a poorly connected ground? Do the symptoms point to a specific ground connection? I stretched a wire from the front RH parking light housing to the alternator bracket screw, with no improvement in the intensity of the light. I believe I remember someone mentioning to ensure that the radiator shroud was securely grounded... perhaps I will try that next.

This type of problem is very common after a complete restore.

The problem is all that nice fresh paint. When I did mone year before last, I had no less than FIVE separate grounding issues, some inter-related.

One of them was the entire rad support, that one bad connection put the charging system at 18 volts and screwed up the entire lighting system, including the tail lights! I fixed that by moving the lil ground igtail off the battery from the inner fender to the rad support, and using a star washer under it.

The best fastest, easiest way to deal with this is go to your local ace hardware and get a handful of external star washers in 1/4" 5/16" & 3/8". Use them under every ground connection bolt, between the terminal and the sheetmetal, not just under the bolthead. Be sure to include the lil ground pigtail off the battery cable, as well as selected sheetmetal, such as some of the rad support to inner fender bolts, and inner fender to fender bolts. The radio interference ground straps from the engine to the body and sub will help too.

Thanks JimM. I'll pick up some star washers tomorrow.

I don't know if the 69 is the same but on my 68 I was having really wierd light and turn signal problems. It turned out to be a ground at the center screw on my instrument cluster. Took a while to track that one down. It seemed like so many unrelated problems to be just one little ground. The assembly manual helped a great deal also!

I have cleaned and carefully tightened all the ground wires, most with star washers, and now I have most of my lights. But, I am blowing the 20A Taillight fuse as fast as I can pop them in there. When I get a chance to work on the car again I'll disconnect the wires from the fuse box back and try to isolate the location of a short. It is puzzling since the whole wiring harness is new and there shouldn't be any shorts.
One thing that I have noticed is that the RH front parking light doesn't burn as bright as the LH. I switched bulbs L to R and R to L and didn't make a difference, so it must be in the socket or the wiring. I may check again that ground connection just above the RH headlight.
I also know that my ground wire from the battery to the alternator bracket does not have the lead to the fender. Based on the above information that could factor into my problem too. I may need to buy a new one the next time that I order from one of the suppliers. I'll get some more star washers too.
Any more suggestions? Am I on the right track?

Are you saying that as soon as you turn your lights on, the rear lights blow the fuse but the fronts stay on? If thats so you may want to check your license plate lamp assy. Maybe the wire got cut and is grounding out. Just disconnect it from the wire harness. Does this also happen when you apply the brakes? Are your front signal light assy's new and repro's? I've had some issues with poor electrical connections from the OER ones. Went with Classic Headquarters and seem alot better. Sounds like your on the right track but still have some grounding issues.

One more thing I would try if none of the above work. Remove all the rear bulbs and turn on the lights. If it still blows the fuse I would say you have a pinched wire or bad harness. If it doesn't blow the fuse, start installing 1 bulb at a time till it does. May be a bad socket even though it is new.

you're on the right track. Check the ground on the dim parking light again. It's real important to have a good ground path from the battery to the sheetmetal, particularly the rad support. I like the repro spring ring cables, they are correct and work good. Another option would be to run a homemade wire from where the big ground cable connects on the engine to the core support.

Lets have some more details on when this fuse blows... My brain isn't coming up with a separate fuse for the tail (running lights) tho it is for the brake lights/turn signals.

The license plate light is a good idea, you can disconnect that in the trunk. Another possibility is the wires to the fuel sender and plate light could be crossed at that same connector in the trunk. Another aid for troubleshooting this would be to disconnect the entire rear light harness at the plug at the top of the drivers side kick panel.

This evening I removed all the rear bulbs and electrical connections, disconnected the line at the tail panel and the fuse box, stuck a fuse in the "Tail/Acc" slot, pulled the light switch, and blew the fuse.
Well at least now I know the short isn't in the rear lights and wiring, but maybe it is under the dash. I spent some time on my back looking under the dash and didn't see anything out of place. I was thinking that this could get real ugly if I have to pull the dash carrier out again.
I then remembered that the dash lights did work at one time, and with that in mind perhaps the problem is in the front parking lights. I disconnected both of the front turn signal lights, stuck a fuse in the slot, pulled the light switch, and my dash lights burned. I connected the front LH parking light and burned the fuse. I disconnected the LH parking light, connected the RH light, and the fuse lived. I have narrowed the problem down to the LH parking light assy. Tomorrow I will pull that puppy out of there and either fix it, or destroy it.
I did place star washers at the remaining grounds and plan to replace the negative battery cable, with the wire to the fender, too. I'll probably be adding a replacement turn signal to that shopping list.
As always, thank you for all the help that you give. It's amazing how quickly someone usually jumps in to help when I post a question.

Wrap up: I took the parking light assembly off the car and with the bulb removed I could see that one of the contacts was laying against the sidewall and the socket was not fully assembled. I popped the center section back and found that the contacts were now more centered. After reassembly and testing I find that all my lights now work properly with one exception.

With no key in the ignition I have a LH turn signal, but not RH. I don't believe either should work without the key turned. Would this be in the wiring in the steering column? This won't keep me off the road, but I do find it puzzling.

Ya that is a strange one. Your right, neither should work with key off. It does sounds like somehow your getting power to one side of the blinker circuit. Possibly the horn circuit. That will be an interesting find.