Guitar Truss Rod Replacement

Does anyone know? Two spare PRS guitar neck?
My friend has a PRS children who came with a guitar neck after-sales on Ebay, and the sound is very good! He argues as you would not believe. He is in love and now I also Here is the strange thing, the neck is in two pieces! The PEG-head seems to be CUT OFF right on the nut. There is this small difference and it looks like some kind of tensor is inside. Moreover, there is a small hole in the bottom of the neck. Weird? Anyway, I was thinking of getting a new neck for my PRS. So, I checked the site and PRS that under no circumstances sell a neck replacement. I'm kind of upset about it, but I'm really intrigued by the neck. Does anyone have any information about it? It is one out? Custom? Any information would be fantastic. I probably like to get one installed on my guitar.
I'm almost positive the neck in question is a Bunker Tension Neck. The neck is actually a bar of cold rolled steel spring, as opposed to a mild steel rod traditional neck truss rod. As you mentioned the neck, in fact, have more sustain, or as we put it to the design "allows" the natural wood tones to pass. The standard, lower neck style Truss Rod inhibits these tones should put pressure on the neck to keep the arm guitar wood stable. You'll find plenty of American made Ibanez guitars, built in the mid-1990s, with this "neck tension," they were made by my guitar company CCP Coopersburg Pa. They add more sustain and tone, you can find more information about how they work: http://bunker-guitars.com/
Making A Guitar Truss Rod