With the Behr radiator, the only thing they do is put a dab of epoxy right on top of the star on the upper tank and color the star with a marker on the sticker. It costs less and is the EXACT same part as Mercedes. It is the OE supplier.
The nissens is not an exact copy, but rather an aftermarket radiator. I have used them and I do like them. They are less costly than the Behr and tend to last longer without tank failure. Some times they are a little challenging to install perfectly, but I have had good results. I sell about 95% OE Behr and 5% nissens. The reason is customer perseption. But, that is OK>
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS