454cid
Sooper Pooper
Before you pull the radiator, you might try tightening the nut on that hard line connection as well. It shouldn't be super tight (you don't want to crack the plastic) but I had one that was leaking on a radiator that was only a year or two old and it ended up being that stamped steel nut was loose. Snugged it up and fixed the leak.
It's worth a shot, even if just to buy some time while waiting for parts to arrive.
My last radiator is a TYC that I've been happy with.