Don, the hose connections on the new radiators are reinforced with a metal insert ... at least on the new Behr radiator I bought for our 300CE. For whatever reason I noticed online that while a new Behr radiator for your 500SL costs $500, a new radiator for a 300CE costs less than $200. The difficulty in repairing the crack is getting the mating surfaces clean enough for an adhesive to hold ... that's assuming there is no way to clamp a patch over the crack. Even a dab of some super adhesive atop the crack is likely to lift off once the cooling system is pressurized.

__________________
Fred Hoelzle