brake booster nipple removal.

[Nodnarb76]

Got my motor in today, and when looking over the motor, looks like I will need to install the nipple into the rear of the intake for my brake booster.
I happen to work for a dealership and we actually had an old intake manifold for my motor laying around.
I could not figure out how to remove the nipple from the manifold. I can't pull it out and it won't unscrew. Any Ideas?