Missing a part from an internally threaded steer tube I recently obtained and then disassemble a Kink Co. BMX. It had a threadless headset. Unexpectedly, instead of having a star nut inside the fork's steer tube, the steer tube was internally threaded (threaded on the inside) and something screwed in. I lost that "something" and have no recollection of what it looked like. What am I working with here? I have never seen a fork like this. I obviously need to replace a part, but can't without any names whatsoever.
I think you're after one of these.

Does the same job as a top cap and star nut but has a hole you can run the front brake line down.