o2 sensor question

[big83chevy4x4]

anyone know what size and thread count the threads are for like a stardard single wire? i need to plug the hole and can't use an o2, i have clearance issues. i really don't want to pull the exhaust to weld it up, its a REAL PITA to get in and out.

 

[readymix]

I know it is 18mm.
Thread pitch I am not so sure of

 

[HarryH3]

Screw an old spark plug into it. They're the same thread.

 

[dyeager535]

M18x1.5