A little side project. (70 Dart)

What did the factory use for the pink primered area where the roof meets the rear quarter, lead? At some point in time I need to address this on my 70 Dart and it seems like an area of flex.
Yes from the factory it is leaded in. Most of the lead is still in this one but, the person before me loaded it up with spot putty...nice!!! I ground it all out and used some metal to metal then, a skim of regular filler and, finished it off with some icing.

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