cant find radiator on pessima mod

i'm working on a (for now) a private mod of the narwhall wagon. now i cant find the radiator in the parts tab. any tips?

also side note/bug suddenly my GUI is really slow in terms of parts menu. is that because i'm working with custom files?

 

I'm unsure on the issue for the radiator, it's possible it's tied to the original engine as a part, but I can't remember for sure, sorry.

As for the parts menu being slow, it's a pretty common thing, and I think it is worse with the more custom files/mods in general you have. A workaround for now is to let it first load and then pause the physics, then you can mess around in it and it will be much faster. Just note that you have to also unpause the game when you're done using the menu for any changes you made in the menu to load