Name of radiator piece where cap screws on?

[SketchyRollin564]

So right now i have a s*** stock radiator in my SR. My friend had a koyo that came with his swap, but the top of it where you screw the cap on to is messed up, sort of stripped, so it screws on kinda funny and leaks at high pressure up there. He didnt feel like dealing with fixing it, so he bought some kids cx racing radiator.

what would you call that piece where the cap screws on? he will sell me the radiator for $50, which is pretty damn cheap. So if i can get a new top piece, i have someone i can pay $20 to weld it on, and ill have an actual koyo aluminum radiator for about $100, which is still cheaper than cxracing or mishimoto.

does anyone know what the proper name for that top piece would be called and where to go about getting a new one? I really doubt they sell that piece separate, but it would be nice to know the name so i could figure something out

or if anyone has any ideas about how to fix it? I know its not the cap, cause for poops and giggles one day when he had it in his car, i tryed my cap which screws on my radiator fine, and it did the same thing and wouldnt want to twist on and seal

[Morph]

The neck?

What exactly is wrong( besides leaking at high pressure, any physical damage say where a hammer was slammed) with it did he drop something on top of it and bend it slightly?

[Warped161]

it's called a radiator fill neck, you can also just shave it off seal it and get an inline hose filler from jegs. just google radiator fill neck.