I've had excellent luck with Reseda Radiator (www.resedaradiator.com). Got a rebuilt Behr for the 300TE and the 733i from them. They basically redo the plastic parts, on the ones I received the upper hose connection was the new-type reinforced with an inner metal sleeve.

No affiliation, just a happy customer. Be sure to specify whether you care if the radiator has been painted on top or not.

Brian
89 300TE 165,xxx
84 733i 5speed 150,xxx