The color of the wires are hard to tell from different but similar colors since the harness is so darn old. The ebay light only had two wires coming out of it, a red and black so I had to add a ground wire and of course I didn't mark it and used a black wire so I'm not 100% sure I have the black wires correct but think if the brake light is working it probably is... Make sense?

GR8 do you mean DC when used as a park light? say parked on side of the road etc. Then AC of the mag when running. Sounds like it's now 12 volt all the way now with vape. I'd better keep out of it or i'll muck ya all up sorry.

Morley, you are helping so feel free to keep spit balling (maybe that's only an American expression), anyway you know a crap load more than I do!

Yes, I think DC means the light will come on just using the light switch and without the engine running.

I don't know anything about the 12v conversions. However, if they use the existing main harness, then I would imagine the tail light would work in the same way as before.

As an aside, and purely an observation and no offence intended here  , but in a new classic car television programme here in the UK, a punter with a big American car had issues with his rear lights - turned out that someone had put one of the dual filament bulbs in the wrong way round (not easily done)! 

Good morning Tony just go down to your local auto parts and get a 1157 bulb

Good morning Wes, I'm going to take a look at the bulb this morning and if it's bad I'll get another but think I may have a spare here somewhere. Have a great day all!

Tested the taillight bulb, it's good.  Also tested for power to both tail light and right rear signal, neither have power at the rear fender connections so I'm guessing my nest move is to check the connections in the headlight bucket.  Have I ever mentioned I hate electrical

Just think of the smarts you are getting sorting out the “spaghetti “bowl!
Follow the wires up to the next connection and check there as well. You’ll get it!
Sneezles61

Thanks Sneezles, after thinking it through that's what I decided to do to see if I can find where I lose power for both taillight and signal, hopefully it's just a bad connection.

You're not alone. Ya can't see electricity until it bites you!!
I can see & hear arcing on the 15000volt power lines going past the gate on a damp night. Used to freak me out. Think they still do it.