1964 Dart Owner - In Over My Head

Here's the ride I'm working with.

So a couple of my concerns that I'm working on at the current time.

Best way to start working through the tail light issue? (I can live with the other wiring and gauge issues for the time being.)

I can't fill the tank up fully because the gasket where the filler neck goes into the tank is weeping when it's full. Is this a simple fix by replacing that gasket? I imagine I can drop the tank slightly to get the tank to slide clear of the filler neck and just replace that gasket?

Also, where's the best place to go looking for the door lock assemblies for the doors? The locks don't work and when I took the trim off to look about working on it, the linkage to the ferrule isn't even there. The locks in the doors are froze up so probably best to just replace all of it.

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