‘68 Dart, One tail light not working.

Mattax said
Do you have the shop manual and parts books? Pretty sure www.mymopar.com has both for '68. I have paper original and CD for 68 so haven't looked but pretty sure mymopar has them.

Yellow insulation was used for dome light return, map light, etc. Orange was typically used for instrument lights including optional tach, shift indicator, etc.
Since there is a delay unit, there could be some other optional or less typical harness connections.

I do not, I’ll give them a look.. I do have a wiring schematic from classiccarwiring.comthe laminated schematic. It’s the indicator bulb. I don’t plan to keep it an automatic in the long term or even in the next year or so. Is there any harm to be done buy not having it ? I found a couple on eBay for $30-$40 that are used but decent shape..