On 2 Aug 2018 05:39:22 GMT, Arlen Holder wrote:

b. Drill it out and helicoil it (nothing to lose really)

Googling, I'm not yet sure a helicoil will work on a through hole.

I think all lambda sensors are 18x1.5 (I'm not sure, but people said that
on the net). Some say it's the same thread as for spark plugs.

If it's the same as for spark plugs, this might work, maybe?
https://shop.advanceautoparts.com/p/...2002/5014964-P

Napa seems to sell a thread chaser for spark plugs, if it's the same thread
as spark plugs...
https://www.napaonline.com/en/p/SER730

This bung might be able to be welded on by a shop if the threads are right:
https://www.diyautotune.com/product/...plug-kit-3735/

The manifold is almost five hundred bucks
https://www.carid.com/eastern-cataly...46&url=4700416