Help locating a certain construction prop piece that is missing from menus.

I need help with this please. This one certain piece that’s used for making stuff, such as trains, has gone missing from the menus ever since GMod 13 came out. It’s still in GMod, you can still spawn it with no problems for Adv. Dupe files that happen to have that piece, but for some reason it’s not showing up in the item construction menus.

Item in question:

Can someone please list the item’s name, or is there some other fix for it?

Isn’t that a phx prop, you could search for phx.

Out of curiosity, what map is that?