Quote Originally Posted by whitefish
condenser is separate but they are bolted together.

The auto tranny lines, the cooler is in the end tank? so if it is, you need an automatic specific radiator.

As for your leak, where is it leaking? I would guess if it was THAT cold, and you turned the drain the plastic might have cracked. Since it had age, and temperature against it. All of your theories "work" though, but where the leak is will let you the problem, not someone guessing on the internet.
At first it was difficult to see exactly where the leak was, but after the engine got up to temp, there was a small stream of antifreeze coming from one of the tubes near the bottom of the rad. The leak was at a fin, which makes me think I may have accidentally damaged the fin which damaged the tube. The leak is not at the plastic drain.
Fins don't leak, but the tubing will, if perforated.

You do see an actual stream of liquid escaping? This is a long shot guess: sometimes, for example if that drain cock is leaking, fluid can be diverted, possibly squirting up in a narrow stream that might appear to be coming from elsewhere. Check the drain cock and particularly the seal on it. If the seal is distorted it will leak.

If it's not the drain cock, you have 3 choices: Add a leak sealant additive and pray it works, remove the radiator and have it professionally repaired, or install a new radiator.