I recently bought the headless bass kit from Pitbull Guitars , however I cannot find the correct wiring diagram for this kit ? Does anyone have a wiring diagram that is correct?
The layout for the SHB-4 should be two volume and one tone, so the YB-4 wiring diagram matches what you need. The only difference is you will (most likely) have 4 wire pickups (plus a bare wire), so you just connect them as per the diagram using black=hot, green+bare=ground (to back of the pot), and insulate the joined red & white tip so it can't short on anything (unless you plan on coil splitting).
Edit: I should mention that the diagram doesn't show it clearly, but the 'folded back' lug on the two volume pots actually indicates a soldered connection to the back on the pot. Either bend the lug and solder it to the back of the pot, or add a wire link from the lug to the back of the pot. The volumes won't work correctly without it.