I'm looking for the part in the book where Das Ganu tells Ratanji to go see Gajanan Maharaj. Which chapter contains this scene?

The source material does not mention Das Ganu advising Ratanji to see Gajanan Maharaj. According to Chapter 14, Ratanji was deeply troubled by his lack of a son and confided in Das Ganu. Das Ganu's advice was explicitly to "Go to Shirdi" to meet Sai Baba. He assured Ratanji that by taking Baba's darshan and surrendering to Him, his heart's desire would be fulfilled. The text emphasizes that Ratanji then resolved to travel to Shirdi to meet Sai Baba, not Gajanan Maharaj, based on this counsel.