Pulling my radiator - basic question

[Mike's money pit]

Well, I am undertaking my first minor project on my truck. It's a 1972 Cheyenne that sat for about 15 years before the original owner's son had it tuned up and sold it to me. It had the water pump replaced a couple of weeks ago and the last time it ran, the radiator developed a leak. The fluid is leaking out the middle area on the front at a pretty good rate.

I have drained the radiator and detached all of the hoses. I have the two metal lines to the transmission still attached. Before I detach these two lines, should I pull the plug on the bottom of the transmission and drain it? Or I thought I might be able to pull the lower line from the radiator at the transmission and drain it there. I am trying to avoid dumping trans fluid in the garage and I don't think I can catch it at the lower hole on the radiator with the frame in the way.

I know this is basic stuff, but this is my first mechanical repair and I would appreciate a little guidance.

Thanks,
Mike