Cold case 756a fitment

Almost everything is made there, you could buy a the $1,000. radiator that's made here, but he didn't. C Case fit my '69 Dart just fine with no issues. I don't even run a shroud on my 418, cools fine, even when it's hot, (90's) plus and humid. Send it back and buy the $1,000. radiator. Be Happy.
I am glad your off shore radiator works well for your application.
The OP is pissed off because he/she was told it will bolt right in and it did not. The OP is part of a growing group of Americans that will no longer support products produced in china.
So, yes you are correct it should be returned and replaced with a radiator that is made in the USA.
Off shore parts have no place in American classic cars.