Spark plug extension on Ford 8N cylinder 3?

[Bigsteve80]

I'm planning on doing a tune-up on my '49 8N. I was looking at the head cover and saw that the spark plug for cylinder #3 has some sort of extension...

The other 3 plugs look normal... sitting on the top of the head. Anyone know what this is before I try unscrewing it? Is it some sort of rethreading device that I've never seen before?
(Sorry for the flashlight picture - by the time I got to taking it, it was pretty dark).

Thanks,
Stephen

 

[CalG]

Just an anti fouling extension. Male and female threaded sleeve. Blow out the crap that might be in the plug well, and start turning.

They can break off, just like a plug can.

Look for an oil wetted plug tip when you get it out. Might have been to compensate for an "oiling" condition.