Confused, 2 Condensers? 230 6cyl dies

[Old65C10]

I recently resurrected this 1965 C10 with a 230 6cyl. It had been sitting a long time. I did al the normal stuff, fluids, brakes, etc.
I replaced the spark plugs, wires, cap, rotor and the condenser in the distributor. This got it running and it was running good for several weeks.
It was running good, but now it will just die. Like you shut if off. Wait a few minutes and it will start again, run for 5 minutes or so and die.
So, I figured it must be the coil. I saw that there is what I assumed a condenser on the coil, so I got a coil and condenser and installed them.
I think it is worse now. No power, want to die, etc.
What is that thing that looks like a condenser attached to the coil? I'm going to guess it is not the condenser I replaced it with.
At this point I am very temped to just put an HEI distributor in it. If you have any suggestions, or where to get a decent drop in HEI, I would be very thankful.