Joining 2 features.

I am attempting to join 2 solid bodies (in the same part file) together to create a single part. In this case, the shank & cutting head of a thread milling hob. What is the most efficient method for accomplishing this task? I have also created and saved an assembly consisting of these 2 bodies. However, I am unclear as to how to join them.

Thanks .

SolidworksParts And Features