I am in the process of sorting a very nice '76 240D that has spent the majority of its years inside and unused. I've driven it a little, test - driving as parts are replaced, etc. I have begun to notice corrosion and the occasional weeping of coolant from the radiator cap. It is almost certainly original to the car, as it is one of the older '100' caps, not the 120 which seems to be all that is available. I do not want to switch to a 120 as the increased opening pressure could be detrimental to the other 40 year old parts. Is there a source for the old 100 cap? Better yet, any way to rebuild or at least try to save the original?