Just because something might be possible to do, doesn't mean it is a good idea to try it.
There is more than you have noticed about the end sections. They hold the rods that hold the sections together. They have a lot of tapping's for the feeds and the air vents. They also make a way to end the fins.
I shouldn't say anything. Some people will try anything to find out it doesn't work.
I was asking specifically about cast iron baseboard radiators. With this info do you still think tap/dye is not the way to go? The sections that I have already have an upper and lower hole to fit a push nipple. Thanks. G
They can be tapped. Why do you want to do this is my question. I have had to due to freeze ups and needing to get the heat on as the end section is toast. I also have sections of New Weil and AmStan I will never get rid of just incase I need them for repairs.