Help! Wiper pivot stud broken

So I just rebuilt all the wiper stuff in the car and go to install and find the driver side wiper pivot stud is broken. I bought the car disassembled so didn't know until now. There is less than 1/4 inch left in the cab. The stud is located in the plenum and looks like the 2 studs are connected by a half moon plate. Has anyone ever had to replace one of these? Is it a threaded stud or like a wheel stud and how do you remove? Twist and turn or knock it out? Thanks, Al