In at least one implementation, a joint for coupling two shafts in a vehicle driveline includes a joint part having a bore defining part of a fluid chamber, a boot member coupled to the joint part and defining at least part of the fluid chamber and having a valve portion that has an open state and a closed state, and an insert. The insert may be received adjacent to the boot member and defines at least part of a vent path that communicates the fluid chamber with the valve portion. When the valve portion is in the closed state venting from the vent chamber is inhibited or prevented and when the valve portion is in the open state the vent chamber is communicated with a venting space.