[defgh1]

You can try to drill out the piece of the bolt and then try to rethread the plenum but you will most likly have to use a helicoil insert to repair the thread.

 

[defgh1]

Do a search on the web on helicoil. Lots of information. You can usually get them at hardware stores or NAPA or Autozone stores.

 

[defgh1]

Your Welcome. Glad I could help.