Update 05/29/2015:
Radiator seal: I've done a whole lot of testing over the past few weeks to figure out exactly where this thing is leaking and trying to reseal it.
First thing was to install a real drain fitting that a hose barb fits on. This lets me empty the radiator without spilling coolant in the ground. This earned me 3 "friend of the environment" points. It also helped out my wallet a bit so I could recycle coolant back in to the radiator after each attempt to seal it. I made over 10 attempts to empty and reseal this thing so it was worth it on both counts.
For what I could see at the time, coolant was slowly making its way out between the hose and the fitting. I tried a few different clamps and a new hose and then decided to pull the radiator again and resolder the fitting extra well just in case the hose wasn't the problem. When it still leaked, I tried the following methods to seal it:
1. Getting better clamps and tightening as much as possible before breaking the clamp.
2. Used some silicone repair tape on the fitting to force the hose to stretch over the barb more when I installed it. This almost worked, but the spot where the tape ends leaves a small void where coolant can seep through.
3. Used black RTV sealant inside the hose and on the fitting. This didn't work any better than raw hose.
4. Used permatex #2 non hardening sealant on both hose and fitting. Actually leaked worse that originally.
5. Used the silicone tape from attempt #2 under the hose clamp to try and add some extra clamping power. Nada...
6. Used two hose clamps to squeeze both sides of the hose nipple in case the hose swelling is contributing to the problem. This seems to help a little bit but not sure.
After the last attempt, I notice that there is coolant actually seeping out from the new solder joint holding the hose fitting to the side tank. There's no crack or missing solder I can see (I've actually soldered plumbing fittings in our last house so I'm not a total newb).
After all that I've determined that the radiator is junk. So last ditch effort to keep things running, I grabbed the 5 minute epoxy and slathered it around the fitting and let it dry. After letting the engine get up to temp, there's no more leak from the fitting or the hose. I'm guessing it was the fitting leaking all along and I just couldn't see it. Here's the ugly repair:
So the plan is to drive it a bit to see if any new leaks pop up after the frame fix. Hopefully that way I can be sure the frame movement was causing the original leaking problems. If that works out to be true, I'll order up a new radiator and hopefully be done.
In other news, I seem to have picked up an extra MPG by replacing my spark plug wires and being careful to route them so they don't cross each other. I used to be able to hear more misfires than I do now so at least something is kinda working.