Here is the answer I got from Bubba over at Titliest Webpage.
Thanks for the question.
Assuming every club, yours and your sons, is a 910, then yes, the shafts are interchangeable. However, it has to be the same type of club, i.e. a driver adapter will not work in a FWY head.
Please let us know if you have any further questions.
Team Titleist Staff