it fits really well, just had to drill 4 holes in the mounting brackets that come welded on to the sides of the radiator. I chose this part # because i wanted to run my tranny cooler separate, instead of running it to the radiator, if you want the "automatic radiator" (w/built-in cooler) the part # is 62012.
We put an Air Mobile direct replacement into our '66, works and looks awesome! I'm not sure how your transmission cooler lines are routed but they can custom make it to fit what you have in there. Not the cheapest but a very nice product. Couldn't find their website and I don't have the part number (we bought ours when they were at the Goodguys in Pleasanton) but here is their contact information:
6407 N 53RD Ave
Glendale, AZ 85301-4612