I don't know about MBs, but I have been able to get new Modine brass/copper radiators for all of my BMWs and my Volvo. They cost about $150-$200, have a lifetime guarantee, and are sold through radiator shops throughout the US and Canada. I've had one in my '82 Volvo 245 for four years now with no problems, and the temp gauge stays below halfway, idling in 90 degree heat with the A/C on. Maybe they make 'em for MBs (or something that could be easily adapted), which would permit you to get rid of those awful plastic things. I have never heard of any make of car which uses plastic rediator tanks and has not had breakage problems. Good luck!