Is it ever appropriate to ask the person leaving the position for which you're interviewing what their salary was?

I'm interviewing with an organization for a Marketing Manager role where the woman leaving the now open Marketing Manager position moved from the marketing department to the communications department

I'm interviewing with an organization for a Marketing Manager role where the woman leaving the now open Marketing Manager position moved from the marketing department to the communications department (all under the MarComm department). The person in the role I'm interviewing for would work with the woman who left it every day, and the director with whom I interviewed earlier this week said the woman leaving the position is wonderful and I'd meet her in the third round if I got to it. Would it be appropriate to ask the woman what her salary was in that role? My guess is she is making more or less the same just moving from Marketing Manager to Communications Manager, so would it be incredibly invasive? I know it may depend on her personality and I should maybe judge based on my feelings of her when I meet her in the next round (assuming I make it to it). So I guess I'm really just looking for someone to say to absolutely never do that.