Thanks Tom,
This oil cooler is the origional from the factory on my 73 B. It has never been taken apart. I think there is some corrosion holding it together.
I soaked it in WD40 and I tried the "plyers" method with two wrenches but it started to distort the metal between the two wrenches.
I wanted to install braded SS steel lines on the cooler, but there is nothing wrong with the hoses on there now. If I can't get it off by heating it, I'll just run it the way it is until I can afford a new one.