New boat, quick question about water distribution tubes

Hey everyone, I just picked up my first inboard boat a few weeks ago. It’s a 1976 Century Sabre with a 318. It uses a raw water cooling system that I am currently going through to variety it’s condition and functionality.
I have a quick question about the brass tubes in the exhaust manifolds. In one manifold the tube spins but does not pull out and on the other it is set and does not rotate. I’m assuring they are not supposed to spin around, but I’m not sure how they are secured in place. Are they pressed in somehow?
Any input would be appreciated, thanks!

Ayuh,.... Got any pictures,..??..??

Yer description is comin' up short,....

Give us some pictures

Here are some photos.
The first is looking from the exhaust end. The copper tube referred to is in the top hole. (she needs some cleaning up)


Here is the side that spins.


Here is the side that does not spin.