"I've seen a fair bit of Greg and I believe he has a promising future," said Hart. "Hopefully he gets as much enjoyment from playing in the No.34 jumper as I did."
Gallman, who is already familiar with Hart after spending time with North Adelaide over the last year, said it was an honour to wear it.
"I was just amazed that a club champion like Ben, who I had gotten to know over the last couple of years, would even think about offering me a number I used to watch out on the park as a youngster," Gallman said.