Oh, damn! And I was thinking that this could be kinky!
I would use JB weld for this and I have done a successful repair with JB weld and a Delrin sleeve made of brass. Epoxy the Delrin sleeve into the radiator and use JB weld to hold the 2 pieces of plastic together. I'm suprised at how well this works!
I have a Nissens and it works great. If you like the Behr, go for it, but the Nissens works fine for me and I live in Arizona where we saw 118*F in the shade last year!
Never got over 100C* with the AC on!